OXYACETYLENE 
WELDING 

AND  CUTTING 

ELECTRIC  AND 
THERMIT  WELDING 

TvlANUY 


Oxy-Acetylene 
Welding  and  Cutting 

Electric,  Forge  and  Thermit 
Welding 

Together  with  Related  Methods  and 
Materials  Used  in  Metal  Working 

And 

The  Oxygen    Process  for 
Removal  of  Carbon 


By 

HAROLD  P.  MANLY 

Chief   Engineer   The   American    Bureau 
of    Engineering 


CHICAGO 

FREDERICK  J .  DRAKE  &  CO. 
Publishers 


Copyright  1916 

By  Frederick  J.  Drake  &  Co. 

Chicago 


PREFACE 

In  the  preparation  of  this  work,  the  object  has  been 
to  cover  not  only  the  several  processes  of  welding,  but 
also  those  other  processes  which  are  so  closely  allied 
in  method  and  results  as  to  make  them,  a  part  of  the 
whole  subject  of  joining  metal  to  metal  with  the  aid 
of  heat. 

The  workman  who  wishes  to  handle  his  trade  from 
start  to  finish  finds  that  it  is  necessary  to  become 
familiar  with  certain  other  operations  which  precede 
or  follow  the  actual  joining  of  the  metal  parts,  the 
purpose  of  these  operations  being  to  add  or  retain 
certain  desirable  qualities  in  the  materials  being  han- 
dled. For  this  reason  the  following  subjects  have 
been  included :  Annealing,  tempering,  hardening,  heat 
treatment  and  the  restoration  of  steel. 

In  order  that  the  user  may  understand  the  under- 
lying principles  and  the  materials  employed  in  this 
work,  much  practical  information  is  given  on  the 
uses  and  characteristics  of  the  various  metals ;  on  the 
production,  handling  and  use  of  the  gases  and  other 
materials  which  are  a  part  of  the  equipment ;  and  on 
the  tools  and  accessories  for  the  production  and  han- 
dling of  these  materials. 

An  examination  will  show  that  the  greatest  useful- 
ness of  this  book  lies  in  the  fact  that  all  necessary 
information  and  data  has  been  included  in  one  vol- 
ume, making  it  possible  for  the  workman  to  use  one 
source  for  securing  a  knowledge  of  both  principle 

343651 


6  <  PREFACE 

and  practice,  preparation  and  finishing  of  the  work, 
and  both  large  and  small  repair  work  as  well  as  manu- 
facturing methods  used  in  metal  working. 

An  effort  has  been  made  to  eliminate  all  matter 
which  is  not  of  direct  usefulness  in  practical  work, 
while  including  all"  that  those  engaged  in  this  trade 
find  necessary.  To  this  end,  the  descriptions  have 
been  limited  to  those  methods  and  accessories  which 
are  found  in  actual  use  today.  For  the.  same  reason, 
the  work  includes  the  application  of  the  rules  laid 
down  by  the  insurance  underwriters  which  govern 
this  work  as  well  as  instructions  for  the  proper  care 
and  handling  of  the  generators,  torches  and  materials 
found  in  the  shop. 

Special  attention  has  been  given  to  definite  direc- 
tions for  handling  the  different  metals  and  alloys 
which  must  be  handled.  The  instructions  have  been 
arranged  to  form  rules  which  are  placed  in  the  order 
of  their  use  during  the  work  described  and  the  work 
has  been  subdivided  in  such  a  wray  that  it  will  be 
found  possible  to  secure  information  on  any  one  point 
desired  without  the  necessity  of  spending  time  in 
other  fields. 

The  facts  which  the  expert  welder  and  metal- 
worker finds  it  most  necessary  to  have  readily  avail- 
able have  been  secured  and  prepared  especially  for 
this  work,  and  those  of  most  general  use  have  been 
combined  with  the  chapter  on  welding  practice  to 
which  they  apply. 

The  size  of  this  volume  has  been  kept  as  small  as 
possible,  but  an  examination  of  the  alphabetical  index 
will  show  that  the  range  of  subjects  and  details  cov- 
ered is  complete  in  all  respects.  This  has  been  accom- 
plished through  careful  classification  of  the  contents 


•PREFACE  7 

and  the  elimination  of  all  repetition  and  all  theoret- 
ical, historical  and  similar  matter  that  is  not  abso- 
lutely necessary. 

Free  use  has  been  made  of  the  information  given 
by  those  manufacturers  who  are  recognized  as  the 
leaders  in  their  respective  fields,  thus  insuring  that 
the  work  is  thoroughly  practical  and  that  it  repre- 
sents present  day  methods  and  practice. 

THE  AUTHOR. 


CONTENTS 

CHAPTER  I 

PAGE 

METALS  AND  ALLOYS — HEAT  TREATMENT: — The  Use  and 
Characteristics  of  the  Industrial  Alloys  and  Metal  Ele- 
ments— Annealing,  Hardening,  Tempering  and  Case  Hard- 
ening of  Steel 11 

CHAPTER  II 

WELDING  MATERIALS  : — Production,  Handling  and  Use  of  the 
Gases,  Oxygen  and  Acetylene — Welding  Eods — Fluxes — 
Supplies  and  Fixtures 33 

CHAPTER  III 

ACETYLENE  GENERATORS: — Generator  Requirements  and 
Types — Construction — Care  and  Operation  of  Generators.  60 

CHAPTER  IV 

WELDING  INSTRUMENTS: — Tank  and  Regulating  Valves  and 
Gauges — High,  Low  and  Medium  Pressure  Torches — Cut- 
ting Torches — Acetylene-Air  Torches 85 

CHAPTER  V 

OXY-ACETYLENE  WELDING  PRACTICE: — Preparation  of  Work 
— Torch  Practice — Control  of  the  Flame — Welding  Vari- 
ous Metals  and  Alloys — Tables  of  Information  Required 
in  Welding  Operations 106 

CHAPTER  VI 

ELECTRIC  WELDING: — Resistance  Method — Butt,  Spot  and 
Lap  Welding — Troubles  and  Remedies — Electric  Arc 

Welding 142 

9 


10  CONTENTS 

CHAPTER  VII 

PAGE 

HAND    FORGING    AND    WELDING: — Blacksmithing,    Forging 
and  Bending — Forge  Welding  Methods 170 

CHAPTER  VIII 

SOLDERING,    BRAZING    AND    THERMIT   WELDING: — Soldering 
Materials   and  Practice — Brazing — Thermit   Welding. ..  .188 

CHAPTER  IX 
OXYGEN  PROCESS  FOR  EEMOVAL  OF  CARBON 207 

INDEX  211 


OXY-ACETYLENE  WELDING  AND 

CUTTING,  ELECTRIC  AND 

THERMIT  WELDING 


CHAPTER  I 

METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT 
THE  METALS 

Iron. — Iron,  in  its  pure  state,  is  a  soft,  white,  easily 
worked  metal.  It  is  the  most  important  of  all  the 
metallic  elements,  and  is,  next  to  aluminum,  the  com- 
monest metal  found  in  the  earth. 

Mechanically  speaking,  we  have  three  kinds  of  iron : 
wrought  iron,  cast  iron  and  steel.  Wrought  iron  is 
very  nearly  pure  iron;  cast  iron  contains  carbon  and 
silicon,  also  chemical  impurities;  and  steel  contains  a 
definite  proportion  of  carbon,  but  in  smaller  quanti- 
ties than  cast  iron. 

Pure  iron  is  never  obtained  commercially,  the  metal 
always  being  mixed  with  various  proportions  of  car- 
bon, silicon,  sulphur,  phosphorus,  and  other  elements, 
making  it  more  or  less  suitable  for  different  purposes. 
Iron  is  magnetic  to  the  extent  that  it  is  attracted  by 
magnets,  but  it  does  not  retain  magnetism  itself,  as 
does  steel.  Iron  forms,  with  other  elements,  many 
important  combinations,  such  as  its  alloys,  oxides, 
and  sulphates. 

11 


12  V/ELDING 

Cast  Iron. — Metallic  iron  is  separated  from  iron 
ore  in  the  blast  furnace  (Figure  1),  and  when  allowed 
to  run  into  moulds  is  called  cast  iron.  This  form  is 
used  for  engine  cylinders  and  pistons,  for  brackets, 
covers,  housings  and  at  any  point  where  its  brittle- 


Figure  1. — Section  Through  a  Blast  Furnace 

ness  is  not  objectionable.  Good  cast  iron  breaks  with 
a  gray  fracture,  is  free  from  blowholes  or  roughness, 
and  is  easily  machined,  drilled,  etc.  Cast  iron  is 
slightly  lighter  than  steel,  melts  at  about  2,400  de- 
grees in  practice,  is  about  one-eighth  as  good  an  elec- 
trical conductor  as  copper  and  has  a  tensile  strength 
of  13,000  to  30,000  pounds  per  square  inch.  Its  com- 


METALS   AND  THEIR  ALLOYS— HEAT  TREATMENT       13 

pressive  strength,  or  resistance  to  crushing,  is  very 
great.  It  has  excellent  wearing  qualities  and  is  not 
easily  warped  and  deformed  by  heat.  Chilled  iron 
is  cast  into  a  metal  mould  so  that  the  outside  is  cooled 
quickly,  making  the  surface  very  hard  and  difficult 
to  cut  and  giving  great  resistance  to  wear.  It  is  used 
for  making  cheap  gear  wheels  and  parts  that  must 
withstand  surface  friction. 

Malleable  Cast  Iron. — This  is  often  called  simply 
malleable  iron.  It  is  a  form  of  cast  iron  obtained  by 
removing  much  of  the  carbon  from  cast  iron,  making 
it  softer  and  less  brittle.  It  has  a  tensile  strength  of 
25,000  to  45,000  pounds  per  square  inch,  is  easily 
machined,  will  stand  a  small  amount  of  bending  at  a 
low  red  heat  and  is  used  chiefly  in  making  brackets, 
fittings  and  supports  where  low  cost  is  of  considerable 
importance.  It  is  often  used  in  cheap  constructions 
in  place  of  steel  forgings.  The  greatest  strength  of  a 
malleable  casting,  like  a  steel  forging,  is  in  the  sur- 
face, therefore  but  little  machining  should  be  done. 

Wrought  Iron. — This  grade  is  made  by  treating  the 
cast  iron  to  remove  almost  all  of  the  carbon,  silicon, 
phosphorus,  sulphur,  manganese  and  other  impuri- 
ties. This  process  leaves  a  small  amount  of  the  slag 
from  the  ore  mixed  with  the  wrought  iron. 

Wrought  iron  is  used  for  making  bars  to  be  ma- 
chined into  various  parts.  If  drawn  through  the  rolls 
at  the  mill  once,  while  being  made,  it  is  called  "muck 
bar;"  if  rolled  twice,  it  is  called  "merchant  bar" 
(the  commonest  kind),  and  a  still  better  grade  is  made 
by  rolling  a  third  time.  Wrought  iron  is  being  grad- 
ually replaced  in  use  by  mild  rolled  steels. 

Wrought  iron  is  slightly  heavier  than  cast  iron,  is 
a  much  better  electrical  conductor  than  either  cast 


14  WELDING 

iron  or  steel,  has  a  tensile  strength  of  40,000  to  60,000 
pounds  per  square  inch  and  costs  slightly  more  than 
steel.  Unlike  either  steel  or  cast  iron,  wrought  iron 
does  not  harden  when  cooled  suddenly  from  a  red  heat. 

Grades  of  Irons. — The  mechanical  properties  of  cast 
iron  differ  greatly  according  to  the  amount  of  other 
materials  it  contains.  The  most  important  of  these 
contained  elements  is  carbon,  which  is  present  to  a 
degree  varying  from  2  to  5%  per  cent.  When  iron 
containing  much  carbon  is  quickly  cooled  and  then 
broken,  the  fracture  is  nearly  white  in  color  and  the 
metal  is  found  to  be  hard  and  brittle.  When  the  iron 
is  slowly  cooled  and  then  broken  the  fracture  is  gray 
and  the  iron  is  more  malleable  and  less  brittle.  If 
cast  iron  contains  sulphur  or  phosphorus,  it  will  show 
a  white  fracture  regardless  of  the  rapidity  of  cooling, 
being  brittle  and  less  desirable  for  general  work. 

Steel. — Steel  is  composed  of  extremely  minute  par- 
ticles of  iron  and  carbon,  forming  a  network  of  layers 
and  bands.  This  carbon  is  a  smaller  proportion  of  the 
metal  than  found  in  cast  iron,  the  percentage  being 
from  T3Q-  to  2!/2  per  cent. 

Carbon  steel  is  specified  according  to  the  number  of 
"points"  of  carbon,  a  point  being  one  one-hundredth 
of  one  per  cent  of  the  weight  of  the  steel.  Steel  may 
contain  anywhere  from  30  to  250  points,  which  is 
equivalent  to  saying,  anywhere  from  -f$  to  2^  per 
cent,  as  above.  A  70-point  steel  would  contain  70/100 
of  one  per  cent  or  TT0-  of  one  per  cent  of  carbon  by 
weight.  The  percentage  of  carbon  determines  the 
hardness  of  the  steel,  also  many  other  qualities,  and 
its  suitability  for  various  kinds  of  work.  The  more 
carbon  contained  in  the  steel,  the  harder  the  metal 
will  be,  and,  of  course,  its  brittleness  increases  with 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT       15 

the  hardness.  The  smaller  the  grains  or  particles  of 
iron  which  are  separated  by  the  carbon,  the  stronger 
the  steel  will  be,  and  the  control  of  the  size  of  these 
particles  is  the  object  of  the  science  of  heat  treatment. 

In  addition  to  the  carbon,  steel  may  contain  the 
following : 
Silicon,    which    increases    the    hardness,    brittleness, 

strength  and  difficulty  of  working  if  from  2  to  3 

per  cent  is  present. 
Phosphorus,  which  hardens  and  weakens  the  metal 

but  makes  it  easier  to  cast.     Three-tenths  per  cent 

of  phosphorus  serves  as  a  hardening  agent  and  may 

be  present  in  good  steel  if  the  percentage  of  carbon 

is  low.    More  than  this  weakens  the  metal. 
Sulphur,  which  tends  to  make  the  metal  hard  and 

filled  with  small  holes. 
Manganese,  which  makes  the  steel  so  hard  and  tough 

that  it  can  with  difficulty  be  cut  with  steel  tools. 

Its  hardness  is  not  lessened  by  annealing,  and  it  has 

great  tensile  strength. 

Alloy  steel  has  a  varying  but  small  percentage  of 
other  elements  mixed  with  it  to  give  certain  desired 
qualities.  Silicon  steel  and  manganese  steel  are  some- 
times classed  as  alloy  steels.  This  subject  is  taken  up 
in  the  latter  part  of  this  chapter  under  Alloys,  where 
the  various  combinations  and  their  characteristics  are 
given  consideration. 

Steel  has  a  tensile  strength  varying  from  50,000  to 
300,000  pounds  per  square  inch,  depending  on  the 
carbon  percentage  and  the  other  alloys  present,  as 
well  as  upon  the  texture  of  the  grain.  Steel  is  heavier 
than  cast  iron  and  weighs  about  the  same  as  wrought 
iron.  It  is  about  one-ninth  as  good  a  conductor  of 
electricity  as  copper. 


16 


WELDING 


Steel  is  made  from  cast  iron  by  three  principal 
processes:  the  crucible,  Bessemer  and  open  hearth. 

Crucible  steel  is  made  by  placing  pieces  of  iron  in 
a  clay  or  graphite  crucible,  mixed  with  charcoal  and  a 
small  amount  of  any  desired  alloy.  The  crucible  is 
then  heated  with  coal,  oil  or  gas  fires  until  the  iron 
melts,  and,  by  absorbing  the  desired  elements  and  giv- 
ing up  or  changing  its  percentage  of  carbon,  becomes 


Figure  2. — A  Bessemer  Converter 

steel.  The  molten  steel  is  then  poured  from  the  cru- 
cible into  moulds  or  bars  for  use.  Crucible  steel  may 
also  be  made  by  placing  crude  steel  in  the  crucibles  in 
place  of  the  iron.  This  last  method  gives  the  finest 
grade  of  metal  and  the  crucible  process  in  general 
gives  the  best  grades  of  steel  for  mechanical  use. 

Bessemer  steel  is  made  by  heating  iron  until  all  the 
undesirable  elements  are  burned  out  by  air  blasts 
which  furnish  the  necessary  oxygen.  The  iron  is 
placed  in  a  large  retort  called  a  converter  (Figure 
2),  being  poured,  while  at  a  melting  heat,  directly 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT        17 

from  the  blast  furnace  into  the  converter.  While  the 
iron  in  the  converter  is  molten,  blasts  of  air  are  forced 
through  the  liquid,  making  it  still  hotter  and  burning 
out  the  impurities  together  with  the  carbon  and  man- 
ganese. These  two  elements  are  then  restored  to  the 
iron  by  adding  spiegeleisen  (an  alloy  of  iron,  carbon 
and  manganese) .  A  converter  holds  from  5  to  25  tons 
of  metal  and  requires  about  20  minutes  to  finish  a 
charge.  This  makes  the  cheapest  steel. 


Figure  3. — An  Open  Hearth  Furnace 

Open  hearth  steel  is  made  by  placing  the  molten 
iron  in  a  receptacle  while  currents  of  air  pass  over  it, 
this  air  having  itself  been  highly  heated  by  just  pass- 
ing over  white  hot  brick  (Figure.  3).  Open  hearth 
steel  is  considered  more  uniform  and  reliable  than 
Bessemer,  and  is  used  for  springs,  bar  steel,  tool  steel, 
steel  plates,  etc. 

Aluminum  is  one  of  the  commonest  industrial 
metals.  It  is  used  for  gear  cases,  engine  crank  cases, 
covers,  fittings,  and  wherever  lightness  and  moderate 
strength  are  desirable. 

Aluminum  is  about  one-third  the  weight  of  iron 


18  WELDING 

and  about  the  same  weight  as  glass  and  porcelain ;  it 
is  a  good  electrical  conductor  (about  one-half  as  good 
as  copper)  ;  is  fairly  strong  itself  and  gives  great 
strength  to  other  metals  when  alloyed  with  them.  One 
of  the  greatest  advantages  of  aluminum  is  that  it  will 
not  rust  or  corrode  under  ordinary  conditions.  The 
granular  formation  of  aluminum  makes  its  strength 
very  unreliable  and  it  is  too  soft  to  resist  wear. 

Copper  is  one  of  the  most  important  metals  used  in 
the  trades,  and  the  best  commercial  conductor  of  elec- 
tricity, being  exceeded  in  this  respect  only  by  silver, 
which  is  but  slightly  better.  Copper  is  very  malleable 
and  ductile  when  cold,  and  in  this  state  may  be  easily 
worked  under  the  hammer.  Working  in  this  way 
makes  the  copper  stronger  and  harder,  but  less  duc- 
tile. Copper  is  not  affected  by  air,  but  acids  cause 
the  formation  of  a  green  deposit  called  verdigris. 

Copper  is  one  of  the  best  conductors  of  heat,  as 
well  as  electricity,  being  used  for  kettles,  boilers,  stills 
and  wherever  this  quality  is  desirable.  Copper  is  also 
used  in  alloys  with  other  metals,  forming  an  impor- 
tant part  of  brass,  bronze,  german  silver,  bell  metal 
and  gun  metal.  It  is  about  one-eighth  heavier  than 
steel  and  has  a  tensile  strength  of  about  25,000  to 
50,000  pounds  per  square  inch. 

Lead. — The  peculiar  properties  of  lead,  and  espe- 
cially its  quality  of  showing  but  little  action  or  chem- 
ical change  in  the  presence  of  other  elements,  makes 
it  valuable  under  certain  conditions  of  use.  Its  prin- 
cipal use  is  in  pipes  for  water  and  gas,  coverings  for 
roofs  and  linings  for  vats  and  tanks.  It  is  also  used 
to  coat  sheet  iron  for  similar  uses  and  as  an  important 
part  of  ordinary  solder. 

Lead  is  the  softest  and  weakest  of  all  the  commer- 


METALS  AND  THEIR   ALLOYS— HEAT  TREATMENT       19 

cial  metals,  being  very  pliable  and  inelastic.  It  should 
be  remembered  that  lead  and  all  its  compounds  are 
poisonous  when  received  into  the  system.  Lead  is 
more  than  one-third  heavier  than  steel,  has  a  tensile 
strength  of  only  about  2,000  pounds  per  square  inch, 
and  is  only  about  one-tenth  as  good  a  conductor  of 
electricity  as  copper. 

Zinc. — This  is  a  bluish-white  metal  of  crystalline 
form.  It  is  brittle  at  ordinary  temperatures  and  be- 
comes malleable  at  about  250  to  300  degrees  Fahren- 
heit, but  beyond  this  point  becomes  even  more  brittle 
than  at  ordinary  temperatures.  Zinc  is  practically 
unaffected  by  air  or  moisture  through  becoming  cov- 
ered with  one  of  its  own  compounds  which  immedi- 
ately resists  further  action.  Zinc  melts  at  low  tem- 
peratures, and  when  heated  beyond  the  melting  point 
gives  off  very  poisonous  fumes. 

The  principal  use  of  zinc  is  as  an  alloy  with  other 
metals  to  form  brass,  bronze,  german  silver  and  bear- 
ing metals.  It  is  also  used  to  cover  the  surface  of 
steel  and  iron  plates,  the  plates  being  then  called 
galvanized. 

Zinc  weighs  slightly  less  than  steel,  has  a  tensile 
strength  of  5,000  pounds  per  square  inch,  and  is  not 
quite  half  as  good  as  copper  in  conducting  electricity. 

Tin  resembles  silver  in  color  and  luster.  Tin  is 
ductile  and  malleable  and  slightly  crystalline  in  form, 
almost  as  heavy  as  steel,  and  has  a  tensile  strength  of 
4,500  pounds  per  square  inch. 

The  principal  use  of  tin  is  for  protective  platings 
on  household  utensils  and  in  wrappings  of  tin-foil. 
Tin  forms  an  important  part  of  many  alloys  such  as 
babbitt,  Britannia  metal,  bronze,  gun  metal  and  bear- 
ing metals. 


20  WELDING 

Nickel  is  important  in  mechanics  because  of  its 
combinations  with  other  metals  as  alloys.  Pure  nickel 
is  grayish-white,  malleable,  ductile  and  tenacious.  It 
weighs  almost  as  much  as  steel  and,  next  to  man- 
ganese, is  the  hardest  of  metals.  Nickel  is  one  of  the 
three  magnetic  metals,  the  others  being  iron  and  co- 
balt. The  commonest  alloy  containing  nickel  is  ger- 
man  silver,  although  one  of  its  most  important  alloys 
is  found  in  nickel  steel.  Nickel  is  about  ten  per  cent 
heavier  -than  steel,  and  has  a  tensile  strength  of  90,000 
pounds  per  square  inch. 

Platinum. — This  metal  is  valuable  for  two  reasons: 
it  is  not  affected  by  the  air  or  moisture  or  any  ordi- 
nary acid  or  salt,  and  in  addition  to  this  property  it 
melts  only  at  the  highest  temperatures.  It  is  a  fairly 
good  electrical  conductor,  being  better  than  iron  or 
steel.  It  is  nearly  three  times  as  heavy  as  steel  and 
its  tensile  strength  is  25,000  pounds  per  square  inch. 

ALLOYS 

An  alloy  is  formed  by  the  union  of  a  metal  with 
some  other  material,  either  metal  or  non-metallic, 
this  union  being  composed  of  two  or  more  elements 
and  usually  brought  about  by  heating  the  substances 
together  until  they  melt  and  unite.  Metals  are  al- 
loyed with  materials  which  have  been  found  to  give 
to  the  metal  certain  characteristics  which  are  desired 
according  to  the  use  the  metal  will  be  put  to. 

The  alloys  of  metals  are,  almost  without  exception, 
more  important  from  an  industrial  standpoint  than 
the  metals  themselves.  There  are  innumerable  pos- 
sible combinations,  the  most  useful  of  which  are  here 
classed  under  the  head  of  the  principal  metal  entering 
into  their  composition. 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT       21 

Steel. — Steel  may  be  alloyed  with  almost  any  of  the 
metals  or  elements,  the  combinations  that  have  proven 
valuable  numbering  more  than  a  score.  The  principal 
ones  are  given  in  alphabetical  order,  as  follows : 

Aluminum  is  added  to  steel  in  very  small  amounts 
for  the  purpose  of  preventing  blow  holes  in  castings. 

Boron  increases  the  density  and  toughness  of  the 
metal. 

Bronze,  added  by  alloying  copper,  tin  and  iron,  is 
used  for  gun  metal. 

Carbon  has  already  been  considered  under  the  head 
of  steel  in  the  section  devoted  to  the  metals.  Carbon, 
while  increasing  the  strength  and  hardness,  decreases 
the  ease  of  forging  and  bending  and  decreases  the 
magnetism  and  electrical  conductivity.  High  carbon 
steel  can  be  welded  only  with  difficulty.  When  the 
percentage  of  carbon  is  low,  the  steel  is  called  "low 
carbon"  or  "mild"  steel.  This  is  used  for  rods  and 
shafts,  and  called  "  machine "  steel.  When  the  car- 
bon percentage  is  high,  the  steel  is  called  "high 
carbon"  steel,  and  it  is  used  in  the  shop  as  tool  steel. 
One-tenth  per  cent  of  carbon  gives  steel  a  tensile 
strength  of  50,000  to  65,000  pounds  per  square  inch ; 
two-tenths  per  cent  gives  from  60,000  to  80,000 ;  four- 
tenths  per  cent  gives  70,000  to  100,000,  and  six-tenths 
per  cent  gives  90,000  to  120,000. 

Chromium  forms  chrome  steel,  and  with  the  further 
addition  of  nickel  is  called  chrome  nickel  steel.  This 
increases  the  hardness  to  a  high  degree  and  adds 
strength  without  much  decrease  in  ductility.  Chrome 
steels  are  used  for  high-speed  cutting  tools,  armor 
plate,  files,  springs,  safes,  dies,  etc. 

Manganese  has  been  mentioned  under  Steel.  Its 
alloy  is  much  used  for  high-speed  cutting  tools,  the 


22  WELDING 

steel  hardening  when  cooled  in  the  air  and  being 
called  self-hardening. 

Molybdenum  is  used  to  increase  the  hardness  to  a 
high  degree  and  makes  the  steel  suitable  for  high- 
speed cutting  and  gives  it  self-hardening  properties. 

Nickel,  with  which  is  often  combined  chromium, 
increases  the  strength,  springiness  and  toughness  and 
helps  to  prevent  corrosion. 

Silicon  has  already  been  described.  It  suits  the 
metal  for  use  in  high-speed  tools. 

Silver  added  to  steel  has  many  of  the  properties 
of  nickel. 

Tungsten  increases  the  hardness  without  making 
the  steel  brittle.  This  makes  the  steel  well  suited  for 
gas  engine  valves  as  it  resists  corrosion  and  pitting. 
Chromium  and  manganese  are  often  used  in  com- 
bination with  tungsten  when  high-speed  cutting  tools 
are  made. 

Vanadium  as  an  alloy  increases  the  elastic  limit, 
making  the  steel  stronger,  tougher  and  harder.  It 
also  makes  the  steel  able  to  stand  much  bending  and 
vibration. 

Copper. — The  principal  copper  alloys  include  brass, 
bronze,  german  silver  and  gun  metal. 

Brass  is  composed  of  approximately  one-third  zinc 
and  two-thirds  copper.  It  is  used  for  bearings  and 
bushings  where  the  speeds  are  slow  and  the  loads 
rather  heavy  for  the  bearing  size.  It  also  finds  use 
in  washers,  collars  and  forms  of  brackets  where  the 
metal  should  be  non-magnetic,  also  for  many  highly 
finished  parts. 

Brass  is  about  one-third  as  good  an  electrical  con- 
ductor as  copper,  is  slightly  heavier  than  steel  and 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT       23 

has  a  tensile  strength  of  15,000  pounds  when  cast 
and  about  75,000  to  100,000  pounds  when  drawn  into 
wire. 

Bronze  is  composed  of  copper  and  tin  in  various 
proportions,  according  to  the  use  to  which  it  is  to 
be  put.  There  will  always  be  from  six-tenths  to  nine- 
tenths  of  copper  in  the  mixture.  Bronze  is  used  for 
bearings,  bushings,  thrust  washers,  brackets  and  gear 
wheels.  It  is  heavier  than  steel,  about  1/15  as  good 
an  electrical  conductor  as  pure  copper  and  has  a 
tensile  strength  of  30,000  to  60,000  pounds. 

Aluminum  bronze,  composed  of  copper,  zinc  and 
•  aluminum  has  high  tensile  strength  combined  with 
ductility  and  is  used  for  parts  requiring  this  com- 
bination. 

Bearing  bronze  is  a  variable  material,  its  composi- 
tion and  proportion  depending  on  the  maker  and  the 
use  for  which  it  is  designed.  It  usually  contains 
from  75  to  85  per  cent  of  copper  combined  with 
one  or  more  elements,  such  as  tin,  zinc,  antimony  and 
lead. 

White  metal  is  one  form  of  bearing  bronze  con- 
taining over  80  per  cent  of  zinc  together  with  cop- 
per, tin,  antimony  and  lead.  Another  form  is  made 
with  nearly  90  per  cent  of  tin  combined  with  copper 
and  antimony. 

Gun  metal  bronze  is  made  from  90  per  cent  copper 
with  10  per  cent  of  tin  and  is  used  for  heavy  bear- 
ings, brackets  and  highly  finished  parts. 

Phosphor  bronze  is  used  for  very  strong  castings 
and  bearings.  It  is  similar  to  gun  metal  bronze, 
except  that  about  l1/^  per  cent  of  phosphorus  has 
been  added. 

Manganese   bronze   contains   about   1  per  cent  of 


24  WELDING 

manganese  and  is  used  for  parts  requiring  great 
strength  while  being  free  from  corrosion. 

German  silver  is  made  from  60  per  cent  of  copper 
with  20  per  cent  each  of  zinc  and  nickel.  Its  high 
electrical  resistance  makes  it  valuable  for  regulating 
devices  and  rheostats. 

Tin  is  the  principal  part  of  babbitt  and  solder.  A 
commonly  used  babbitt  is  composed  of  89  per  cent  tin, 
8  per  cent  antimony  and  3  per  cent  of  copper.  A 
grade  suitable  for  repairing  is  made  from  80  per 
cent  of  lead  and  20  per  cent  antimony.  This  last 
formula  should  not  be  used  for  particular  work  or 
heavy  loads,  being  more  suitable  for  spacers.  In- 
numerable proportions  of  metals  are  marketed  under 
the  name  of  babbitt. 

Solder  is  made  from  50  per  cent  tin  and  50  per  cent 
lead,  this  grade  being  called  "half-and-half."  Hard 
solder  is  made  from  two-thirds  tin  and  one-third 
lead. 

Aluminum  forms  many  different  alloys,  giving  in- 
creased strength  to  whatever  metal  it  unites  with. 

Aluminum  brass  is  composed  of  approximately  65 
per  cent  copper,  30  per  cent  zinc  and  5  per  cent  alu- 
minum. It  forms  a  metal  with  high  tensile  strength 
while  being  ductile  and  malleable. 

Aluminum  zinc  is  suitable  for  castings  which  must 
be  stiff  and  hard. 

Nickel  aluminum  has  a  tensile  strength  of  40,000 
pounds  per  square  inch. 

Magnalium  is  a  silver-white  alloy  of  aluminum 
with  from  5  to  20  per  cent  of  magnesium,  forming 
a  'metal  even  lighter  than  aluminum  and  strong 
enough  to  be  used  in  making  high-speed  gasoline 
engines. 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT       25 
HEAT  TREATMENT  OF  STEEL 

The  processes  of  heat  treatment  are  designed  to 
suit  the  steel  for  various  purposes  by  changing  the 
size  of  the  grain  in  the  metal,  therefore  the  strength ; 
and  by  altering  the  chemical  composition  of  the  al- 
loys in  the  metal  to  give  it  different  physical  prop- 
erties. Heat  treatment,  as  applied  in  ordinary  shop 
work,  includes  the  three  processes  of  annealing,  hard- 
ening and  tempering,  each  designed  to  accomplish  a 
certain  definite  result. 

All  of  these  processes  require  that  the  metal  treated 
be  gradually  brought  to  a  certain  predetermined 
degree  of  heat  which  shall  be  uniform  throughout  the 
piece  being  handled  and,  from  this  point,  cooled  ac- 
cording to  certain  rules,  the  selection  of  wrhich  forms 
the  difference  in  the  three  methods. 

Annealing. — This  is  the  process  which  relieves  all 
internal  strains  and  distortion  in  the  metal  and 
softens  it  so  that  it  may  more  easily  be  cut,  machined 
or  bent  to  the  required  form.  In  some  cases  anneal- 
ing is  used  only  to  relieve  the  strains,  this  being  the 
case  after  forging  or  welding  operations  have  been 
performed.  In  other  cases  it  is  only  desired  to  soften 
the  metal  sufficiently  that  it  may  be  handled  easily. 
In  some  cases  both  of  these  things  must  be  accom- 
plished, as  after  a  piece  has  been  forged  and  must 
be  machined.  No  matter  what  the  object,  the  pro- 
cedure is  the  same. 

The  steel  to  be  annealed  must  first  be  heated  to  a 
dull  red.  This  heating  should  be  done  slowly  so 
that  all  parts  of  the  piece  have  time  to  reach  the  same 
temperature  at  very  nearly  the  same  time.  The  piece 
may  be  heated  in  the  forge,  but  a  much  better  way  is 


26  WELDING 

to  heat  in  an  oven  or  furnace  of  some  type  where 
the  work  is  protected  against  air  currents,  either  hot 
or  cold,  and  is  also  protected  against  the  direct  action 
of  the  fire. 

Probably  the  simplest  of  all  ovens  for  small  tools  is 
made  by  placing  a  piece  of  ordinary  gas  pipe  in  the 
fire  (Figure  4),  and  heating  until  the  inside  of  the 
pipe  is  bright  red.  Parts  placed  in  this  pipe,  after 
one  end  has  been  closed,  may  be  brought  to  the  de- 


Figure  4. — A  Gaspipe  Annealing  Oven 

sired  heat  without  danger  of  cooling  draughts  or 
chemical  change  from  the  action  of  the  fire.  More 
elaborate  ovens  may  be  bought  which  use  gas,  fuel 
oils  or  coal  to  produce  the  heat  and  in  which  the 
work  may  be  placed  on  trays  so  that  the  fire  will  not 
strike  directly  on  the  steel  being  treated. 

If  the  work  is  not  very  important,  it  may  be  with- 
drawn from  the  fire  or  oven^,  after  heating  to  the 
desired  point,  and  allowed  to  cool  in  the  air  until  all 
traces  of  red  have  disappeared  when  held  in  a  dark 
place.  The  work  should  be  held  where  it  is  reason- 
ably free  from  cold  air  currents.  If,  upon  touching 
a  pine  stick  to  the  piece  being  annealed,  the  wood 


METALS   AND  THEIR  ALLOYS— HEAT  TREATMENT       27 

does  not  smoke,  the  work  may  then  be  cooled  in 
water. 

Better  annealing  is  secured  and  harder  metal  may 
be  annealed  if  the  cooling  is  extended  over  a  number 
of  hours  by  placing  the  work  in  a  bed  of  non-heat- 
conducting  material,  such  as  ashes,  charred  bone, 
asbestos  fibre,  lime,  sand  or  fire  clay.  It  should  be 
well  covered  with  the  heat  retaining  material  and 
allowed  to  remain  until  cool.  Cooling  may  be  accom- 
plished by  allowing  the  fire  in  an  oven  or  furnace 
to  die  down  and  go  out,  leaving  the  work  inside  the 
oven  with  all  openings  closed.  The  greater  the  time 
taken  for  gradual  cooling  from  the  red  heat,  the 
more  perfect  will  be  the  results  of  the  annealing. 

While  steel  is  annealed  by  slow  cooling,  copper  or 
brass  is  annealed  by  bringing  to  a  low  red  heat  and 
quickly  plunging  into  cold  water. 

Hardening. — Steel  is  hardened  by  bringing  to  a 
proper  temperature,  slowly  and  evenly  as  for  an- 
nealing, and  then  cooling  more  or  less  quickly,  ac- 
cording to  the  grade  of  steel  being  handled.  The 
degree  of  hardening  is  determined  by  the  kind  of 
steel,  the  temperature  from  which  the  metal  is  cooled 
and  the  temperature  and  nature  of  the  bath  into 
which  it  is  plunged  for  cooling. 

Steel  to  be  hardened  is  often  heated  in  the  fire 
until  at  some  heat  around  600  to  700  degrees  is 
reached,  then  placed  in  a  heating  bath  of  molten  lead, 
heated  mercury,  fused  cyanate  of  potassium,  etc.,  the 
heating  bath  itself  being  kept  at  the  proper  tempera- 
ture by  fires  acting  on  it.  While  these  baths  have 
the  advantage  of  heating  the  metal  evenly  and  to 
exactly  the  temperature  desired  throughout  without 
any  part  becoming  over  or  under  heated,  their  dis- 


28  WELDING 

advantages  consist  of  the  fact  that  their  materials 
and  the  fumes  are  poisonous  in  most  all  cases,  and  if 
not  poisonous,  are  extremely  disagreeable. 

The  degree  of  heat  that  a  piece  of  steel  must  be 
brought  to  in  order  that  it  may  be  hardened  depends 
on  the  percentage  of  carbon  in  the  steel.  The  greater 
the  percentage  of  carbon,  the  lower  the  heat  neces- 
sary to  harden. 

To  find  the  proper  heat  from  which  any  steel  must 
be  cooled,  a  simple  test  may  be  carried  out  provided 


Figure  5. — Cooling  the  Test  Bar  for  Hardening 

a  sample  of  the  steel,  about  six  inches  long  can  be 
secured.  One  end  of  this  test  bar  should  be  heated 
almost  to  its  melting  point,  and  held  at  this  heat 
until  the  other  end  just  turns  red.  Now  cool  the 
piece  in  water  by  plunging  it  so  that  both  ends 
enter  at  the  same  time  (Figure  5),  that  is,  hold  it 
parallel  with  the  surface  of  the  water  when  plunged 
in.  This  serves  the  purpose  of  cooling  each  point 
along  the  bar  from  a  different  heat.  When  it  has 
cooled  in  the  water  remove  the  piece  and  break  it  at 
short  intervals,  about  y2  inch,  along  its  length.  The 
point  along  the  test  bar  which  was  cooled  from  the 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT        29 

best  possible  temperature  will  show  a  very  fine 
smooth  grain  and  the  piece  cannot  be  cut  by  a  file 
at  this  point.  It  will  be  necessary  to  remember  the 
exact  color  of  that  point  when  taken  from  the  fire, 
making  another  test  if  necessary,  and  heat  all  pieces 
of  this  same  steel  to  this  heat.  It  will  be  necessary 
to  have  the  cooling  bath  always  at  the  same  tempera- 
ture, or  the  results  cannot  be  alike. 

While  steel  to  be  hardened  is  usually  cooled  in 
water,  many  other  liquids  may  be  used.  If  cooled 
in  strong  brine,  the  heat  will  be  extracted  much 
quicker,  and  the  degree  of  hardness  will  be  greater. 
A  still  greater  degree  of  hardness  is  secured  by  cool- 
ing in  a  bath  of  mercury.  Care  should  be  used  with 
the  mercury  bath,  as  the  fumes  that  arise  are  poi- 
sonous. 

Should  toughness  be  desired,  without  extreme  hard- 
ness, the  steel  may  be  cooled  in  a  bath  of  lard  oil, 
neatsfoot  oil  or  fish  oil.  To  secure  a  result  between 
water  and  oil,  it  is  customary  to  place  a  thick  layer 
of  oil  on  top  of  water.  In  cooling,  the  piece  will  pass 
thrugh  the  oil  first,  thus  avoiding  the  sudden  shock 
of  the  cold  water,  yet  producing  a  degree  of  hard- 
ness almost  as  great  as  if  the  oil  were  not  used. 

It  will,  of  course,  be  necessary  to  make  a  separate 
test  for  each  cooling  medium  used.  If  the  fracture  of 
the  test  piece  shows  a  coarse  grain,  the  steel  was  too 
hot  at  that  point;  if  the  fracture  can  be  cut  with  a 
file,  the  metal  was  not  hot  enough  at  that  point. 

When  hardening  carbon  tool  steel  its  heat  should 
be  brought  to  a  cherry  red,  the  exact  degree  of  heat 
depending  on  the  amount  of  carbon  and  the  test  made, 
then  plunged  into  water  and  held  there  until  all 
hissing  sound  and  vibration  ceases.  Brine  may  be 


30  WELDING 

used  for  this  purpose;  it  is  even  better  than  plain 
water.  As  soon  as  the  hissing  stops,  remove  the 
work  from  the  water  or  brine  and  plunge  in  oil 
for  complete  cooling. 

In  hardening  high-speed  tool  steel,  or  air  hardening 
steels,  the  tool  should  be  handled  as  for  carbon  steel, 
except  that  after  the  body  reaches  a  cherry  red,  the 
cutting  point  must  be  quickly  brought  to  a  white  heat, 


Figure  6. — Cooling  the  Tool  for  Tempering 

almost  melting,  so  that  it  seems  ready  for  welding. 
Then  cool  in  an  oil  bath  or  in  a  current  of  cool  air. 

Hardening  of  copper,  brass  and  bronze  is  accom- 
plished by  hammering  or  working  them  while  cold. 

Tempering  is  the  process  of  making  steel  tough 
after  it  has  been  hardened,  so  that  it  will  hold  a 
cutting  edge  and  resist  cracking.  Tempering  makes 
the  grain  finer  and  the  metal  stronger.  It  does  not 
affect  the  hardness,  but  increases  the  elastic  limit 
and  reduces  the  brittleness  of  the  steel.  In  that  tem- 
pering is  usually  performed  immediately  after  har- 


METALS  AND  THEIR  ALLOYS— HEAT  TREATMENT   31 

dening,  it  might  be  considered  as  a  continuation  of 
the  former  process. 

The  work  or  tool  to  be  tempered  is  slowly  heated  to 
a  cherry  red  and  the  cutting  end  is  then  dipped  into 
water  to  a  depth  of  y%  to  %  inch  above  the  point 
(Figure  6).  As  soon  as  the  point  cools,  still  leaving 
the  tool  red  above  the  part  in  water,  remove  the 
work  from  the  bath  and  quickly  rub  the  end  with  a 
fine  emery  cloth. 

As  the  heat  from  the  uncooled  part  gradually  heats 
the  point  again,  the  color  of  the  polished  portion 
changes  rapidly.  When  a  certain  color  is  reached, 
the  tool  should  be  completely  immersed  in  the  water 
until  cold. 

For  lathe,  planer,  shaper  and  slotter  tools,  this 
color  should  be  a  light  straw. 

Reamers  and  taps  should  be  cooled  from  an  ordi- 
nary straw  color. 

Drills,  punches  and  wood  working  tools  should 
have  a  brown  color. 

Blue  or  light  purple  is  right  for  cold  chisels  and 
screwdrivers. 

Dark  blue  should  be  reached  for  springs  and  wood 
saws. 

Darker  colors  than  this,  ranging  through  green  and 
gray,  denote  that  the  piece  has  reached  its  ordinary 
temper,  that  is,  it  is  partially  annealed. 

After  properly  hardening  a  spring  by  dipping  in 
lard  or  fish  oil.  it  should  be  held  over  a  fire  while 
still  wet  with  the  oil.  The  oil  takes  fire  and  burns 
off,  properly  tempering  the  spring. 

Remember  that  self -hardening  steels  must  never  be 
dipped  in  water,  and  always  remember  for  all  work 


32  WELDING 

requiring  degrees  of  heat,  that  the  more  carbon,  the 
less  heat. 

Case  Hardening. — This  is  a  process  for  adding 
more  carbon  to  the  surface  of  a  piece  of  steel,  so  that 
it  will  have  good  wear-resisting  qualities,  while  being 
tough  and  strong  on  the  inside.  It  has  the  effect  of 
forming  a  very  hard  and  durable  skin  on  the  surface 
of  soft  steel,  leaving  the  inside  unaffected. 

The  simplest  way,  although  not  the  most  efficient, 
is  to  heat  the  piece  to  be  case  hardened  to  a  red 
heat  and  then  sprinkle  or  rub  the  part  of  the  surface 
to  be  hardened  with  potassium  ferrocyanide.  This 
material  is  a  deadly  poison  and  should  be  handled 
with  care.  Allow  the  cyanide  to  fuse  on  the  surface 
of  the  metal  and  then  plunge  into  water,  brine  or 
mercury.  Eepeating  the  process  makes  the  surface 
harder  and  the  hard  skin  deeper  each  time. 

Another  method  consists  of  placing  the  piece  to 
be  hardened  in  a  bed  of  powdered  bone  (bone  which 
has  been  burned  and  then  powdered)  and  cover  with 
more  powdered  bone,  holding  the  whole  in  an  iron 
tray.  Now  heat  the  tray  and  bone  with  the  work 
in  an  oven  to  a  bright  red  heat  for  30  minutes  to  an 
hour  and  then  plunge  the  work  into  water  or  brine. 


CHAPTER  II 

OXY-ACETYLENE  WELDING  AND   CUTTING 
MATERIALS 

Welding. — Oxy-acetylene  welding  is  an  autogenous 
welding  process,  in  which  two  parts  of  the  same  or 
different  metals  are  joined  by  causing  the  edges  to 
melt  and  unite  while  molten  without  the  aid  of 
hammering  or  compression.  When  cool,  the  parts 
form  one  piece  of  metal. 

The  oxy-acetylene  flame  is  made  by  mixing  oxygen 
and  acetylene  gases  in  a  special  welding  torch  or 
blowpipe,  producing,  when  burned,  a  heat  of  6,300 
degrees,  which  is  more  than  twice  the  melting  tem- 
perature of  the  common  metals.  This  flame,  while 
being  of  intense  heat,  is  of  very  small  size. 

Cutting. — The  process  of  cutting  metals  with  the 
flame  produced  from  oxygen  and  acetylene  depends 
on  the  fact  that  a  jet  of  oxygen  directed  upon  hot 
metal  causes  the  metal  itself  to  burn  away  with  great 
rapidity,  resulting  in  a  narrow  slot  through  the  sec- 
tion cut.  The  action  is  so  fast  that  metal  is  not  in- 
jured on  either  side  of  the  cut. 

Carbon  Removal. — This  process  depends  on  the 
fact  that  carbon  will  burn  and  almost  completely 
vanish  if  the  action  is  assisted  with  a  supply  of  pure 
oxygen  gas.  After  the  combustion  is  started  with 
any  convenient  flame,  it  continues  as  long  as  carbon 
remains  in  the  path  of  the  jet  of  oxygen. 

Materials. — For  the  performance  of  the  above  oper- 
ations we  require  the  two  gases,  oxygen  and  acetylene, 
to  produce  the  flames;  rods  of  metal  which  may  be 
added  to  the  joints  while  molten  in  order  to  give 

33 


34  WELDING 

the  weld  sufficient  strength  and  proper  form,  and  va- 
rious chemical  powders,  called  fluxes,  which  assist 
in  the  flow  of  metal  and  in  doing  away  with  many 
of  the  impurities  and  other  objectionable  features. 

Instruments. — To  control  the  combustion  of  the 
gases  and  add  to  the  convenience  of  the  operator  a 
number  of  accessories  are  required. 

The  pressure  of  the  gases  in  their  usual  containers 
is  much  too  high  for  their  proper  use  in  the  torch 
and  we  therefore  need  suitable  valves  which  allow  the 
gas  to  escape  from  the  containers  when  wanted,  and 
other  specially  designed  valves  which  reduce  the 
pressure.  Hose,  composed  of  rubber  and  fabric,  to- 
gether with  suitable  connections,  is  used  to  carry  the 
gas  to  the  torch. 

The  torches  for  welding  and  cutting  form  a  class  of 
highly  developed  instruments  of  the  greatest  accuracy 
in  manufacture,  and  must  be  thoroughly  understood 
by  the  welder.  Tables,  stands  and  special  supports 
are  provided  for  holding  the  work  while  being  welded, 
and  in  order  to  handle  the  various  metals  and  allow 
for  their  peculiarities  while  heated  use  is  made  of 
ovens  and  torches  for  preheating.  The  operator  re- 
quires the  protection  of  goggles,  masks,  gloves  and 
appliances  which  prevent  undue  radiation  of  the  heat. 

Torch  Practice. — The  actual  work  of  welding  and 
cutting  requires  preliminary  preparation  in  the  form 
of  heat  treatment  for  the  metals,  including  preheat- 
ing, annealing  and  tempering.  The  surfaces  to  be 
joined  must  be  properly  prepared  for  the  flame,  and 
the  operation  of  the  torches  for  best  results  requires 
careful  and  correct  regulation  of  the  gases  and  the 
flame  produced. 

Finally,  the  different  metals  that  are  to  be  welded 


OXY-ACETYLENE   WELDING   AND   CUTTING  MATERIALS  35 

require  special  treatment  for  each  one,  depending  on 
the  physical  and  chemical  characteristics  of  the  ma- 
terial. 

It  will  thus  be  seen  that  the  apparently  simple 
operations  of  welding  and  cutting  require  special 
materials,  instruments  and  preparation  on  the  part 
of  the  operator  and  it  is  a  proved  fact  that  failures, 
which  have  been  attributed  to  the  method,  are  really 
due  to  lack  of  these  necessary  qualifications. 
OXYGEN 

Oxygen,  the  gas  which  supports  the  rapid  combus- 
tion of  the  acetylene  in  the  torch  flame,  is  one  of 
the  elements  of  the  air.  It  is  the  cause  and  the  active 
agent  of  all  combustion  that  takes  place  in  the  at- 
mosphere. Oxygen  was  first  discovered  as  a  separate 
gas  in  1774,  when  it  was  produced  by  heating  red 
oxide  of  mercury  and  was  given  its  present  name  by 
the  famous  chemist,  Lavoisier. 

Oxygen  is  prepared  in  the  laboratory  by  various 
methods,  these  including  the  heating  of  chloride  of 
lime  and  'peroxide  of  cobalt  mixed  in  a  retort,  the 
heating  of  chlorate  of  potash,  and  the  separation  of 
water  into  its  elements,  hydrogen  and  oxygen,  by  the 
passage  of  an  electric  current.  While  the  last  process 
is  used  on  a  large  scale  in  commercial  work,  the 
others  are  not  practical  for  work  other  than  that  of 
an  experimental  or  temporary  nature. 

This  gas  is  a  colorless,  odorless,  tasteless  element. 
It  is  sixteen  times  as  heavy  as  the  gas  hydrogen  when 
measured  by  volume  under  the  same  temperature  and 
pressure.  Under  all  ordinary  conditions  oxygen 
remains  in  a  gaseous  form,  although  it  turns  to  a 
liquid  when  compressed  to  4,400  pounds  to  the  square 
inch  and  at  a  temperature  of  220°  below  zero. 


36  WELDING 

Oxygen  unites  with  almost  every  other  element, 
this  union  often  taking  place  with  great  heat  and 
much  light,  producing  flame.  Steel  and  iron  will 
burn  rapidly  when  placed  in  this  gas  if  the  combus- 
tion is  started  with  a  flame  of  high  heat  playing  on 
the  metal.  If  the  end  of  a  wire  is  heated  bright  red 
and  quickly  plunged  into  a  jar  containing  this  gas, 
the  wire  will  burn  away  with  a  dazzling  light  and  be 
entirely  consumed  except  for  the  molten  drops  that 
separate  themselves.  This  property  of  oxygen  is  used 
in  oxy-acetylene  cutting  of  steel. 

The  combination  of  oxygen  with  other  substances 
does  not  necessarily  cause  great  heat,  in  fact  the  com- 
bination may  be  so  slow  and  gradual  that  the  change 
of  temperature  can  not  be  noticed.  An  example  of 
this  slow  combustion,  or  oxidation,  is  found  in  the' 
conversion  of  iron  into  rust  as  the  metal  combines 
with  the  active  gas.  The  respiration  of  human  beings 
and  animals  is  a  form  of  slow  combustion  and  is  the 
source  of  animal  heat.  It  is  a  general  rule  that  the 
process  of  oxidation  takes  place  with  increasing  rapid- 
ity as  the  temperature  of  the  body  being  acted  upon 
rises.  Iron  and  steel  at  a  red  heat  oxidize  rapidly 
with  the  formation  of  a  scale  and  possible  damage  to 
the  metal. 

Air. — Atmospheric  air  is  a  mixture  of  oxygen  and 
nitrogen  with  traces  of  carbonic  acid  gas  and  water 
vapor.  Twenty-one  per  cent  of  the  air,  by  volume, 
is  oxygen  and  the  remaining  seventy-nine  per  cent 
is  the  inactive  gas,  nitrogen.  But  for  the  presence 
of  the  nitrogen,  which  deadens  the  action  of  the  other 
gas,  combustion  would  take  place  at  a  destructive 
rate  and  be  beyond  human  control  in  almost  all  cases. 
These  two  gases  exist  simply  as  a  mixture  to  form  the 


OXY-ACETYLENE   WELDING   AND  CUTTING  MATERIALS  37 

air  and  are  not  chemically  combined.  It  is  there- 
fore a  comparatively  simple  matter  to  separate  them 
with  the  processes  now  available. 

Water. — Water  is  a  combination  of  oxygen  and 
hydrogen,  being  composed  of  exactly  two  volumes  of 
hydrogen  to  one  volume  of  oxygen.  If  these  two  gases 


Figure  7. — Obtaining  Oxygen  by  Electrolysis 

be  separated  from  each  other  and  then  allowed  to 
mix  in  these,  proportions  they  unite  with  explosive 
violence  and  form  water.  Water  itself  may  be  sepa- 
rated into  the  gases  by  any  one  of  several  means, 
one  making  use  of  a  temperature  of  2,200°  to  bring 
about  this  separation. 

The  easiest  way  to  separate  water  into  its  two  parts 
is  by  the  process  called  electrolysis  (Figure  7).  Water, 


38  WELDING 

with  which  has  been  mixed  a  small  quantity  of  acid, 
is  placed  in  a  vat  through  the  walls  of  which  enter  the 
platinum  tipped  ends  of  two  electrical  conductors,  one 
positive  and  the  other  negative. 

Tubes  are  placed  directly  above  these  wire  ter- 
minals in  the  vat,  one  tube  being  over  each  electrode 
and  separated  from  each  other  by  some  distance. 
With  the  passage  of  an  electric  current  from  one  wire 
terminal  to  the  other,  bubbles  of  gas  rise  from  each 
and  pass  into  the  tubes.  The  gas  that  comes  from 
the  negative  terminal  is  hydrogen  and  that  from 
the  positive  pole  is  oxygen,  both  gases  being  almost 
pure  if  the  work  is  properly  conducted.  This  method 
produces  electrolytic  oxygen  and  electrolytic  hydro- 
gen. 

The  Liquid  Air  Process. — While  several  of  the 
foregoing  methods  of  securing  oxygen  are  success- 
ful as  far  as  this  result  is  concerned,  they  are  not 
profitable  from  a  financial  standpoint.  A  process 
for  separating  oxygen  from  the  nitrogen  in  the  air 
has  been  brought  to  a  high  state  of  perfection  and  is 
now  supplying  a  major  part  of  this  gas  for  oxy- 
acetylene  welding.  It  is  known  as  the  Linde  process 
and  the  gas  is  distributed  by  the  Linde  Air  Products 
Company  from  its  plants  and  warehouses  located  in 
/the  large  cities  of  the  country. 

The  air  is  first  liquefied  by  compression,  after  which 
the  gases  are  separated  and  the  oxygen  collected.  The 
air  is  purified  and  then  compressed  by  successive 
stages  in  powerful  machines  designed  for  this  pur- 
pose until  it  reaches  a,  pressure  of  about  3,000  pounds 
to  the  square  inch.  The  large  amount  of  heat  pro- 
duced is  absorbed  by  special  coolers  during  the 
process  of  compression.  The  highly  compressed  air  is 


OXY-ACETYLENE   WELDING   AND   CUTTING  MATERIALS  39 

then  dried  and  the  temperature  further  reduced  by 
other  coolers. 

The  next  point  in  the  separation  is  that  at  which 
the  air  is  introduced  into  an  apparatus  called  an  in- 
terchanger  and  is  allowed  to  escape  through  a  valve, 
causing  it  to  turn  to  a  liquid.  This  liquid  air  is 
sprayed  onto  plates  and  as  it  falls,  the  nitrogen  re- 
turn to  its  gaseous  state  arid  leaves  the  oxygen  to 
run  to  the  bottom  of  the  container.  This  liquid 
oxygen  is  then  allowed  to  return  to  a  gas  and  is 
stored  in  large  gasometers  or  tanks. 

The  oxygen  gas  is  taken  from  the  storage  tanks  and 
compressed  to  approximately  1,800  pounds  to  the 
square  inch,  under  which  pressure  it  is  passed  into 
steel  cylinders  and  made  ready  for  delivery  to  the 
customer.  This  oxygen  is  guaranteed  to  be  ninety- 
seven  per  cent  pure. 

Another  process,  known  as  the  Hildebrandt  process, 
is  coming  into  use  in  this  country.  It  is  a  later  process 
and  is  used  in  Germany  to  a  much  greater  extent  than 
the  Linde  process.  The  Superior  Oxygen  Co.  has 
secured  the  American  rights  and  has  established  sev- 
eral plants. 

Oxygen  Cylinders. — Two  sizes  of  cylinders  are  in 
use,  one  containing  100  cubic  feet  of  gas  when  it  is 
at  atmospheric  pressure  and  the  other  containing  250 
cubic  feet  under  similar  conditions.  The  cylinders 
are  made  from  one  piece  of  steel  and  are  without 
seams.  These  containers  are  tested  at  double  the  pres- 
sure of  the  gas  contained  to  insure  safety  while 
handling. 

One  hundred  cubic  feet  of  oxygen  weighs  nearly 
nine  pounds  (8.921),  and  therefore  the  cylinders 
will  we:'""1"1  fVally  nine  pounds  more  when  full 


40  WELDING 

than  after  emptying,  if  of  the  100  cubic  feet  size. 
The  large  cylinders  weigh  about  eighteen  and  one- 
quarter  pounds  more  when  full  than  when  empty, 
making  approximately  212  pounds  empty  and  230 
pounds  full. 

The  following  table  gives  the  number  of  cubic  feet 
of  oxygen  remaining  in  the  cylinders  according  to 
various  gauge  pressures  from  an  initial  pressure  of 
1,800  pounds.  The  amounts  given  are  not  exactly 
correct  as  this  would  necessitate  lengthy  calculations 
which  would  not  make  great  enough  difference  to 
affect  the  practical  usefulness  of  the  table  : 

Cylinder  of  100  Cu.  Ft.  Capacity  at  68°  Fahr. 

Gauge  Volume  Gauge  Volume 

Pressure  Remaining  Pressure  Remaining 

1800  100  700  39 

1620  90  500  28 

1440  80  300  17 

1260  70  100  6 

1080  60  18  1 

900  50  9  % 


Cylinder  of  250  Cu.  Ft.   Capacity  at  68°  Fahr. 

Gauge  Volume  Gauge  Volume 

Pressure  Remaining  Pressure  Remaining 

1800  250  700  9-7 

1620  225  500  70 

1440  200  300  42 

1260  175  100  15 

1080  150  18                           8 

900  125  9                           1% 

The  temperature  of  the  cylinder  affects  the  pressure 
in  a  large  degree,  the  pressure  increasing  with  a  rise 
in  temperature  and  falling  with  a  fall  in  temperature. 
The  variation  for  a  100  cubic  foot  cylinder  at  various 
temperatures  is  given  in  the  following  tabulation  : 


OXY-ACETYLENE  WELDING  AND  CUTTING  MATERIALS  41 

At  150°  Fahr 2090  pounds. 

At  100°  Fahr 1912  pounds. 

At     80°  Fahr 1844  pounds. 

At     68°  Fahr 1800  pounds. 

At     50°  Fahr 1736  pounds. 

At     32°  Fahr 1672  pounds. 

At       0     Fahr 1558  pounds. 

At — 10°  Fahr 1522  pounds. 

Chlorate  of  Potash  Method. — In  spite  of  its  higher 
cost  and  the  inferior  gas  produced,  the  chlorate  of 
potash  method  of  producing  oxygen  is  used  to  a 


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Figure  8. — Oxygen  from  Chlorate  of  Potash 

limited  extent  when  it  is  impossible  to  secure  the  gas 
in  cylinders. 

An  iron  retort  (Figure  8)  is  arranged  to  receive 
about  fifteen  pounds  of  chlorate  of  potash  mixed  with 
three  pounds  of  manganese  dioxide,  after  which  the 
cylinder  is  closed  with  a  tight  cap,  clamped  on.  This 
retort  is  carried  above  a  burner  using  fuel  gas  or 
other  means  of  generating  heat  and  this  burner  is 
lighted  after  the  chemical  charge  is  mixed  and  com- 
pressed in  the  tube. 

The  generation  of  gas  commences  and  the  oxygen  is 
led  through  water  baths  which  wash  and  cool  it 


42  WELDING 

before  storing  in  a  tank  connected  with  the  plant. 
From  this  tank  the  gas  is  compressed  into  portable 
cylinders  at  a  pressure  of  about  300  pounds  to  the 
square  inch  for  use  as  required  in  welding  operations. 

Each  pound  of  chlorate  of  potash  liberates  about 
three  cubic  feet  of  oxygen,  and  taking  everything  into 
consideration,  the  cost  of  gas  produced  in  this  way  is 
several  times  that  of  the  purer  product  secured  by 
the  liquid  air  process. 

These  chemical  generators  are  oftentimes  a  source 
of  great  danger,  especially  when  used  with  or  near 
the  acetylene  gas  generator,  as  is  sometimes  the  case 
with  cheap  portable  outfits.  Their  use  should  not  be 
tolerated  when  any  other  method  is  available,  as  the 
danger  from  accident  alone  should  prohibit  the  prac- 
tice except  when  properly  installed  and  cared  for 
away  from  other  sources  of  combustible  gases. 

ACETYLENE 

In  1862  a  chemist,  Woehler,  announced  the  dis- 
covery of  the  preparation  of  acetylene  gas  from  cal- 
cium carbide,  which  he  had  made  by  heating  to  a  high 
temperature  a  mixture  of  charcoal  with  an  alloy  of 
zinc  and  calcium.  His  product  would  decompose 
water  and  yield  the  gas.  For  nearly  thirty  years  these 
substances  were  neglected,  with  the  result  that  acety- 
lene was  practically  unknown,  and  up  to  1892  an 
acetylene  flame  was  seen  by  very  few  persons  and 
its  possibilities  were  not  dreamed  of.  "With  the  de- 
velopment of  the  modern  electric  furnace  the  possi- 
bility of  calcium  carbide  as  a  commercial  product 
became  known. 

In  the  above  year,  Thomas  L.  "Willson,  an  electrical 
engineer  of  Spray,  North  Carolina,  was  experiment- 


OXY-ACETYLENE   WELDING  AND   CUTTING  MATERIALS  43 

ing  in  an  attempt  to  prepare  metallic  calcium,  for 
which  purpose  he  employed  an  electric  furnace  oper- 
ating on  a  mixture  of  lime  and  coal  tar  with  about 
ninety-five  horse  power.  The  result  was  a  molten 
mass  which  became  hard  and  brittle  when  cool.  This 
apparently  useless  product  was  discarded  and  thrown 
in  a  nearby  stream,  when,  to  the  astonisment  of  on- 
lookers, a  large  volume  of  gas  was  immediately  lib- 
erated, which,  when  ignited,  burned  with  a  bright 
and  smoky  flame  and  gave  off  quantities  of  soot. 
The  solid  material  proved  to  be  calcium  carbide  and 
the  gas  acetylene. 

Thus,  through  the  incidental  study  of  a  by-product, 
and  as  the  result  of  an  accident,  the  possibilities  in 
carbide  were  made  known,  and  in  the  spring  of  1895 
the  first  factory  in  the  world  for  the  production  of 
this  substance  was  established  by  the  Willson  Alumi- 
num Company. 

When  water  and  calcium  carbide  are  brought  to- 
gether an  action  takes  place  which  results  in  the  for- 
mation of  acetylene  gas  and  slaked  lime. 

CARBIDE 

Calcium  carbide  is  a  chemical  combination  of  the 
elements  carbon  and  calcium,  being  dark  brown,  black 
or  gray  with  sometimes  a  blue  or  red  tinge.  It 
looks  like  stone  and  will  only  burn  when  heated  with 
oxygen. 

Calcium  carbide  may  be  preserved  for  any  length 
of  time  if  protected  from  the  air,  but  the  ordinary 
moisture  in  the  atmosphere  gradually  affects  it  until 
nothing  remains  but  slaked  lime.  It  always  possesses 
a  penetrating  odor,  which  is  not  due  to  the  carbide 
itself  but  to  the  fact  that  it  is  being  constantly  af- 


44  WELDING 

fected  by  moisture  and  producing  small  quantities  of 
acetylene  gas. 

This  material  is  not  readily  dissolved  by  liquids, 
but  if  allowed  to  come  in  contact  with  water,  a  de- 
composition takes  place  with  the  evolution  of  large 
quantities  of  gas.  Carbide  is  not  affected  by  shock, 
jarring  or  age. 

A  pound  of  absolutely  pure  carbide  will  yield  five 
and  one-half  cubic  feet  of  acetylene.  Absolute  purity 
cannot  be  attained  commercially,  and  in  practice  good 
carbide  will  produce  from  four  and  one-half  to  five 
cubic  feet  for  each  pound  used. 

Carbide  is  prepared  by  fusing  lime  and  carbon  in 
the  electric  furnace  under  a  heat  in  excess  of  6,000° 
Fahrenheit.  These  materials  are  among  the  most  diffi- 
cult to  melt  that  are  known.  Lime  is  so  infusible  that 
it  is  frequently  employed  for  the  materials  of  cruci- 
bles in  which  the  highest  melting  metals  are  fused, 
and  for  the  pencils  in  the  calcium  light  because  it  will 
stand  extremely  high  temperatures. 

Carbon  is  the  material  employed  in  the  manufac- 
ture of  arc  light  electrodes  and  other  electrical  appli- 
ances that  must  stand  extreme  heat.  Yet  these  two 
substances  are  forced  into  combination  in  the  manu- 
facture of  calcium  carbide.  It  is  the  excessively  high 
temperature  attainable  in  the  electric  furnace  that 
causes  this  combination  and  not  any  effect  of  the  elec- 
tricity other  than  the  heat  produced. 

A  mixture  of  ground  coke  and  lime  is  introduced 
into  the  furnace  through  which  an  electric  arc  has 
been  drawn.  The  materials  unite  and  form  an  ingot 
of  very  pure  carbide  surrounded  by  a  crust  of  less 
purity.  The  poorer  crust  is  rejected  in  breaking  up 
the  mass  into  lumps  which  are  graded  according  to 


OXY-ACETYLENE   WELDING  AND  CUTTING  MATERIALS  45 


their  size.  The  largest  size  is  2  by  3y2  inches  and 
is  called  "lump,"  a  medium  size  is  y2  by  2  inches  and 
is  called  '  '  egg,  '  '  an  intermediate  size  for  certain  types 
of  generators  is  %  by  1^4  inches  and  called  "nut," 
and  the  finely  crushed  pieces  for  use  in  still  other 
types  of  generators  are  1/12  by  14  inch  in  size  and 
are  called  "quarter."  Instructions  as  to  the  size  best 
suited  to  different  generators  are  furnished  by  the 
makers  of  those  instruments. 

These  sizes  are  packed  in  air-tight  sheet  steel  drums 
containing  100  pounds  each.  The  Union  Carbide 
Company  of  Chicago  and  New  York,  operating  under 
patents,  manufactures  and  distributes  the  supply  of 
calcium  carbide  for  the  entire  United  States.  Plants 
for  this  manufacture  are  established  at  Niagara  Falls, 
New  York,  and  Sault  Ste.  Marie,  Michigan.  This 
company  maintains  a  system  of  warehouses  in  more 
than  one  hundred  and  ten  cities,  where  large  stocks 
of  all  sizes  are  carried. 

The  National  Board  of  Fire  Underwriters  gives  the 
following  rules  for  the  storage  of  carbide: 

Calcium  carbide  in  quantities  not  to  exceed  six 
hundred  pounds  may  be  stored,  when  contained  in 
approved  metal  packages  not,  to  exceed  one  hundred 
pounds  each,  inside  insured  property,  provided  that 
the  place  of  storage  be  dry,  waterproof  and  well  ven- 
tilated and  also  provided  that  all  but  one  of  the 
packages  in  any  one  building  shall  be  sealed  and 
that  seals  shall  not  be  broken  so  long  as  there  is  car- 
bide in  excess  of  one  pound  in  any  other  unsealed 
package  in  the  building. 

Calcium  carbide  in  quantities  in  excess  of  six  hun- 
dred pounds  must  be  stored  above  ground  in  detached 
buildings,  used  exclusively  for  the  storage  of  cal- 


46  WELDING 

cium  carbide,  in  approved  metal  packages,  and  such 
buildings  shall  be  constructed  to  be  dry,  waterproof 
and  well  ventilated. 

Properties  of  Acetylene. — This  gas  is  composed  of 
twenty-four  parts  of  carbon  and  two  parts  of  hydro- 
.gen  by  weight  and  is  classed  with  natural  gas,  petro- 
leum, etc.,  as  one  of  the  hydrocarbons.  This  gas  con- 
tains the  highest  percentage  of  carbon  known  to  exist 
in  any  combination  of  this  form  and  it  may  there- 
fore be  considered  as  gaseous  carbon.  Carbon  is  the 
fuel  that  is  used  in  all  forms  of  combustion  and  is 
present  in  all  fuels  from  whatever  source  or  in  what- 
ever form.  Acetylene  is  therefore  the  most  power- 
ful of  all  fuel  gases  and  is  able  to  give  to  the  torch 
flame  in  welding  the  highest  temperature  of  any 
flame. 

Acetylene  is  a  colorless  and  tasteless  gas,  possessed 
of  a  peculiar  and  penetrating  odor.  The  least  trace 
in  the  air  of  a  room  is  easily  noticed,  and  if  this  odor 
is  detected  about  an  apparatus  in  operation,  it  is 
certain  to  indicate  a  leakage  of  gas  through  faulty 
piping,  open  valves,  broken  hose  or  otherwise.  This 
leakage  must  be  prevented  before  proceeding  with  the 
work  to  be  done. 

All  gases  which  burn  in  air  will,  when  mixed  with 
air  previous  to  ignition,  produce  more  or  less  vio- 
lent explosions,  if  fired.  To  this  rule  acetylene  is  no 
exception.  One  measure  of  acetylene  and  twelve  and 
one-half  of  air  are  required  for  complete  combustion ; 
this  is  therefore  the  proportion  for  the  most  perfect 
explosion.  This  is  not  the  only  possible  mixture  that 
will  explode,  for  all  proportions  from  three  to  thirty 
per  cent  of  acetylene  in  air  will  explode  with  more 
or  less  force  if  ignited. 


OXY-ACETYLENE  WELDING  AND  CUTTING  MATERIALS  47 

The  igniting  point  of  acetylene  is  lower  than  that 
of  coal  gas,  being  about  900  degrees  Fahrenheit  as 
against  eleven  hundred  degrees  for  coal  gas.  The 
gas  issuing  from  a  torch  will  ignite  if  allowed  to  play 
on  the  tip  of  a  lighted  cigar. 

It  is  still  further  true  that  acetylene,  at  some  pres- 
sures, greater  than  normal,  has  under  most  favorable 
conditions  for  the  effect,  been  found  to  explode ;  yet 
it  may  be  stated  with  perfect  confidence  that  under  no 
circumstances  has  anyone  ever  secured  an  explosion 
in  it  when  subjected  to  pressures  not  exceeding  fif- 
teen pounds  to  the  square  inch. 

Although  not  exploded  by  the  application  of  high 
heat,  acetylene  is  injured  by  such  treatment.  It  is 
partly  converted,  by  high  heat,  into  other  compounds, 
thus  lessening  the  actual  quantity  of  the  gas,  wasting 
it  and  polluting  the  rest  by  the  introduction  of  sub- 
stances which  do  not  belong  there.  These  compounds 
remain  in  part  with  the  gas,  causing  it  to  burn  with 
a  persistent  smoky  flame  and  with  the  deposit  of 
objectionable  tarry  substances.  Where  the  gas  is  gen- 
erated without  undue  rise  of  temperature  these  diffi- 
culties are  avoided. 

Purification  of  Acetylene. — Impurities  in  this  gas 
are  caused  by  impurities  in  the  calcium  carbide  from 
which  it  is  made  or  by  improper  methods  and  lack  of 
care  in  generation.  Impurities  from  the  material 
will  be  considered  first. 

Impurities  in  the  carbide  may  be  further  divided 
into  two  classes:  those  which  exert  no  action  on  wrater 
and  those  which  act  with  the  water  to  throw  off 
other  gaseous  products  which  remain  in  the  acetylene. 
Those  impurities  which  exert  no  action  on  the  water 
consist  of  coke  that  has  not  been  changed  in  the 


48  WELDING 

furnace  and  sand  and  some  other  substances  which 
are  harmless  except  that  they  increase  the  ash  left 
after  the  acetylene  has  been  generated. 

An  analysis  of  the  gas  coming  from  a  typical  gen- 
erator is  as  follows: 

Per  cent 

Acetylene 99.36 

Oxygen   08 

Nitrogen    11 

Hydrogen    06 

Sulphuretted  Hydrogen  . 17 

Phosphoretted  Hydrogen 04 

Ammonia    10 

Silicon  Hydride 03 

Carbon  Monoxide 01 

Methane    04 

The  oxygen,  nitrogen,  hydrogen,  methane  and  car- 
bon monoxide  are  either  harmless  or  are  present  in 
such  small  quantities  as  to  be  neglected.  The  phos- 
phoretted  hydrogen  and  silicon  hydride  are  self- 
inflammable  gases  when  exposed  to  the  air,  but  their 
quantity  is  so  very  small  that  this  possibility  may  be 
dismissed.  The  ammonia  and  sulphuretted  hydrogen 
are  almost  entirely  dissolved  by  the  water  used  in 
the  gas  generator.  The  surest  way  to  avoid  impure 
gas  is  to  use  high-grade  calcium  carbide  in  the  gener- 
ator and  the  carbide  of  American  manufacture  is 
now  so  pure  that  it  never  causes  trouble. 

The  first  and  most  important  purification  to  which 
the  gas  is  subjected  is  its  passage  through  the  body 
of  water  in  the  generator  as  it  bubbles  to  the  top. 
It  is  then  filtered  through  felt  to  remove  the  solid 


OXY-ACETYLENE   WELDING   AND   CUTTING   MATERIALS  49 

particles  of  lime  dust  and  other  impurities  which 
float  in  the  gas. 

Further  purification  to  remove  the  remaining  am- 
monia, sulphuretted  hydrogen  and  phosphorus  con- 
taining compounds  is  accomplished  by  chemical 
means.  If  this  is  considered  necessary  it  can  be  easily 
accomplished  by  readily  available  purifying  appa- 
ratus which  can  be  attached  to  any  generator  or  in- 
serted between  the  generator  and  torch  outlets.  The 
following  mixtures  have  been  used. 

"Heratol,"  a  solution  of  chromic  acid  or  sulphuric 
acid  absorbed  in  porous  earth. 

"Acagine,"  a  mixture  of  bleaching  powder  with 
fifteen  per  cent  of  lead  chromate. 

"Puratylene,"  a  mixture  of  bleaching  powder  and 
hydroxide  of  lime,  made  very  porous,  and  containing 
from  eighteen  to  twenty  per  cent  of  active  chlorine. 

"FrQnkoline,"  a  mixture  of  cuprous  and  ferric 
chlorides  dissolved  in  strong  hydrochloric  acid  ab- 
sorbed in  infusorial  earth. 

A  test  for  impure  acetylene  gas  is  made  by  placing 
a  drop  of  ten  per  cent  solution  of  silver  nitrate  on 
a  white  blotter  and  holding  the  paper  in  a  stream  of 
gas  coming  from  the  torch  tip.  Blackening  of  the 
paper  in  a  short  length  of  time  indicates  impurities. 

Acetylene  in  Tanks. — Acetylene  is  soluble  in  water 
to  a  very  limited  extent,  too  limited  to  be  of  prac- 
tical use.  There  is  only  one  liquid  that  possesses 
sufficient  power  of  containing  acetylene  in  solution 
to  be  of  commercial  value,  this  being  the  liquid  ace- 
tone. Acetone  is  produced  in  various  ways,  often- 
times from  the  distillation  of  wood.  It  is  a  trans- 
parent, colorless  liquid  that  flows  with  ease.  It  boils 
at  133°  Fahrenheit,  is  inflammable  and  burns  with 


50  WELDING 

a  luminous  flame.  It  has  a  peculiar  but  rather  agree- 
able odor. 

Acetone  dissolves  twenty-four  times  its  own  bulk  of 
acetylene  at  ordinary  atmospheric  pressure.  If  this 
pressure  is  increased  to  two  atmospheres,  14.7  pounds 
above  ordinary  pressure,  it  will  dissolve  just  twice  as 
much  of  the  gas  and  for  each  atmosphere  that  the 
pressure  is  increased  it  will  dissolve  as  much  more. 

If  acetylene  be  compressed  above  fifteen  pounds 
per  square  inch  at  ordinary  temperature  without  first 
being  dissolved  in  acetone  a  danger  is  present  of  self- 
ignition.  This  danger,  while  practically  nothing  at 
fifteen  pounds,  increases  with  the  pressure  until  at 
forty  atmospheres  it  is  very  explosive.  Mixed  with 
acetone,  the  gas  loses  this  dangerous  property  and  is 
safe  for  handling  and  transportation.  As  acetylene  is 
dissolved  in  the  liquid  the  acetone  increases  its  vol- 
ume slightly  so  that  when  the  gas  has  been  drawn  out 
of  a  closed  tank  a  space  is  left  full  of  free  acetylene. 

This  last  difficulty  is  removed  by  first  filling  the 
cylinder  or  tank  with  some  porous  material,  such  as 
asbestos,  wrood  charcoal,  infusorial  earth,  etc.  As- 
bestos is  used  in  practice  and  by  a  system  of  packing 
and  supporting  the  absorbent  material  no  space  is 
left  for  the  free  gas,  even  when  the  acetylene  has. 
been  completely  withdrawn. 

The  acetylene  is  generated  in  the  usual  way  and  is 
washed,  purified  and  dried.  Great  care  is  used  to 
make  the  gas  as  free  as  possible  from  all  impurities 
and  from  air.  The  gas  is  forced  into  containers 
filled  with  acetone  as  described  and  is  compressed  to 
one  hundred  and  fifty  pounds  to  the  square  inch. 
From  these  tanks  it  is  transferred  to  the  smaller  port- 
able cvlinders  for  consumers '  use. 


OXY-ACETYLBNE   WELDING  AND  CUTTING  MATERIALS  51 

The  exact  volume  of  gas  remaining  in  a  cylinder  at 
atmospheric  temperature  may  be  calculated  if  the 
weight  of  the  cylinder  empty  is  known.  One  pound 
of  the  gas  occupies  13.6  cubic  feet,  so  that  if  the 
difference  in  weight  between  the  empty  cylinder  and 
the  one  considered  be  multiplied  by  13.6,  the  result 
will  be  the  number  of  cubic  feet  of  gas  contained. 

The  cylinders  contain  from  100  to  500  cubic  feet 
of  acetylene  under  pressure.  They  cannot  be  filled 
with  the  ordinary  type  of  generator  as  they  require 
special  purifying  and  compressing  apparatus,  which 
should  never  be  installed  in  any  building  where  other 
work  is  being  carried  on,  or  near  other  buildings 
which  are  occupied,  because  of  the  danger  of  ex- 
plosion. 

Dissolved  acetylene  is  manufactured  by  the  Prest- 
0-Lite    Company,    the    Commercial   Acetylene    Com-, 
pany  and  the  Searchlight  Gas  Company  and  is  dis- 
tributed from  warehouses  in  various  cities. 

These  tanks  should  not  be  discharged  at  a  rate  per 
hour  greater  than  one-seventh  of  their  total  capacity, 
that  is,  from  a  tank  of  100  cubic  feet  capacity,  the 
discharge  should  not  be  more  than  fourteen  cubic 
feet  per  hour.  If  discharge  is  carried  on  at  an  ex- 
cessive rate  the  acetone  is  drawn  out  with  the 
and  reduces  the  heat  of  the  welding  flame. 

For  this  reason  welding  should  not  be  attempted 
with  cylinders  designed  for  automobile  and  boat 
lighting.  When  the  work  demands  a  greater  delivery 
than  one  of  the  larger  tanks  will  give,  two  or  more 
tanks  may  be  connected  with  a  special  coupler  such  as 
may  be  secured  from  the  makers  and  distributers  of 
the  gas.  These  couplers  may  be  arranged  for  two, 
three,  four  or  five  tanks  in  one  battery  by  removing 


52  WELDING 

the  plugs  on  the  body  of  the  coupler  and  attaching 
additional  connecting  pipes.  The  coupler  body  car- 
ries a  pressure  gauge  and  the  valve  for  controlling 
the  pressure  of  the  gas  as  it  flows  to  the  welding 
torches.  The  following  capacities  should  be  provided 
for: 

Acetylene  Consumption  Combined  Capacity  of 

of  Torches  per  Hour  Cylinders  in  Use 

Up  to  15  feet 100  cubic  feet 

16  to  30  feet 200  cubic  feet 

31  to  45  feet 300  cubic  feet 

46  to  60  feet 400  cubic  feet 

61  to  75  feet 500  cubic  feet 

WELDING  RODS 

The  best  welding  cannot  be  done  without  using  the 
best  grade  of  materials,  and  the  added  cost  of  these 
materials  over  less  desirable  forms  is  so  slight  when 
compared  to  the  quality  of  work  performed  and  the 
waste  of  gases  with  inferior  supplies,  that  it  is  very 
unprofitable  to  take  any  chances  in  this  respect.  The 
makers  of  welding  equipment  carry  an  assortment  of 
supplies  that  have  been  standardized  and  that  may 
be  relied  upon  to  produce  the  desired  result  when 
properly  used.  The  safest  plan  is  to  secure  this  class 
of  material  from  the  makers. 

"Welding  rods,  or  welding  sticks,  are  used  to  supply 
the  additional  metal  required  in  the  body  of  the  weld 
to  replace  that  broken  or  cut  away  and  also  to  add 
to  the  joint  whenever  possible  so  that  the  work  may 
have  the  same  or  greater  strength  than  that  found  in 
the  original  piece.  A  rod  of  the  same  material  as 


OXY-ACETYLENE  WELDING  AND  CUTTING  MATERIALS  53 

that  being  welded  is  used  when  both  parts  of  the  work 
are  the  same.  When  dissimilar  metals  are  to  be  joined  x 
rods  of  a  composition  suited  to  the  work  are  em- 
ployed. 

These  filling  rods  are  required  in  all  work  except 
steel  of  less  than  16  gauge.  Alloy  iron  rods  are  usedV 
for  cast  iron.  These  rods  have  a  high  silicon  content, 
the  silicon  reacting  with  the  carbon  in  the  iron  to 
produce  a  softer  and  more  easily  machined  weld  than 
would  otherwise  be  the  case.  These  rods  are  often 
made  so  that  they  melt  at  a  slightly  lower  point  than 
cast  iron.  This  is  done  for  the  reason  that  when  the 
part  being  welded  has  been  brought  to  the  fusing  heat 
by  the  torch,  the  filling  material  can  be  instantly 
melted  in  without  allowing  the  parts  to  cool.  The 
metal  can  be  added  faster  and  more  easily  controlled. 

Rods  or  wires  of  Jforwyron  are  used  for  steel 


^ 

welding  in  almost  all  cases.  The  purity  of  this  grade  1 
of  iron  gives  a  homogeneous,  soft  weld  of  even  texture, 
great  ductility  and  exceptionally  good  machining 
qualities.  For  welding  heavy  steel  castings,  a  rod  of 
rolled  carbon  steel  is  employed.  For  working  on  high 
carbon  steel,  a  rod  of  the  steel  being  welded  must  be 
employed  and  for  alloy  steels,  such  as  nickel,  man- 
ganese, vanadium,  etc.,  special  rods  of  suitable  alloy 
composition  are  preferable. 

Aluminum  welding  rods  are  made  from  this  metal 

alloyed  to   give   the  even  flowing  that  is  essential. 

<  Aluminum  is  one  of  the  most  difficult  of  all  the  metals 

to  handle  in  this  work  and  the  selection  of  the  proper 

rod  is  of  great  importance. 

Brass  is  filled  with  brass  wire  when  in  small  cast- 
ings and  sheets.  For  general  work  with  brass  castings, 
manganese  bronze  or  Tobin  bronze  may  be  used. 


54  WELDING 

Bronze  is  welded  with  manganese  bronze  or  Tobin 
bronze,  while  copper  is  filled  with  copper  wire. 

These  welding  rods  should  always  be  used  to  fill 
the  weld  when  the  thickness  of  material  makes  their 
employment  necessary,  and  additional  metal  should 
always  be  added  at  the  weld  when  possible  as  the 
joint  cannot  have  the  same  strength  as  the  original 
piece  if  made  or  dressed  off  flush  with  the  surfaces 
around  the  weld.  This  is  true  because  the  metal 
welded  into  the  joint  is  a  casting  and  will  never  have 
more  strength  than  a  casting  of  the  material  used  for 
filling. 

Great  care  should  be  exercised  when  adding  metal 
from  welding  rods  to  make  sure  that  no  metal  is 
added  at  a  point  that  is  not  itself  melted  and  molten 
when  the  addition  is  made.  When  molten  metal  is 
placed  upon  cooler  siirfaces  the  result  is  not  a  weld 
but  merely  a  sticking  together  of  the  two  parts  with- 
out any  strength  in  the  joint. 

FLUXES 

Difficulty  would  be  experienced  in  welding  with 
only  the  metal  and  rod  to  work  with  because  of  the 
scale  that  forms  on  many  materials  under  heat,  the 
oxides  of  other  metals  and  the  impurities  found  in 
almost  all  metals.  These  things  tend  to  prevent  a 
perfect  joining  of  the  metals  and  some  means  are 
necessary  to  prevent  their  action. 

Various  chemicals,  usually  in  powder  form,  are 
used  to  accomplish  the  result  of  cleaning  the  weld 
and  making  the  work  of  the  operator  less  difficult. 
They  are  called  fluxes. 

^     A  flux  is  used  to  float  off  physical  impurities  from 
the   molten  metal;   to   furnish   a  protecting   coating 


OXY-ACETYLENE   WELDING   AND  CUTTING  MATERIALS  55 

around  the  weld ;  to  assist  in  the  removal  of  any  ob- 
jectionable oxide  of  the  metals  being  handled ;  to 
lower  the  temperature  at  which  the  materials  flow ;  to 
make  a  cleaner  weld  and  to  produce  a  better  quality 
of  metal  in  the  finished  work. 

The  flux  must  be  of  such  composition  that  it  will 
accomplish  the  desired  result  without  introducing 
new  difficulties.  They  may  be  prepared  by  the  oper- 
ator in  many  cases  or  may  be  secured  from  the  mak- 
ers of  welding  apparatus,  the  same  remarks  applying 
to  their  quality  as  were  made  regarding  the  welding 
rods,  that  is,  only  the  best  should  be  considered. 
4-The  flux  used  for  cast  iron  should  have  a  softening 
effect  and  should  prevent  burning  of  the  metal.  In 
many  cases  it  is  possible  and  even  preferable  to  weld 
cast  iron  without  the  use  of  a  flux,  and  in  any  event 
the  smaller  the  quantity  used  the  better  the  result 
should  be.  Flux  should  not  be  added  just  before  the 
completion  of  the  work  because  the  heat  will  not  have 
time  to  drive  the  added  elements  out  of  the  metal  or 
to  incorporate  them  with  the  metal  properly. 

/Aluminum  should  never  be  welded  without  using 
a  flux  because  of  the  oxide  formed.  This  oxide,  called 
alumina,  does  not  melt  until  a  heat  of  5,000°  Fahren- 
heit is  reached,  four  times  the  heat  needed  to  melt  the 
aluminum  itself.  It  is  necessary  that  this  oxide  be 
broken  down  or  dissolved  so  that  the  aluminum  may 
have  a  chance  to  flow  together.  Copper  is  another 
metal  that  requires  a  flux  because  of  its  rapid,  oxida- 
tion under  heat. 

While  the  flux  is  often  thrown  or  sprinkled  along 
the  break  while  welding,  much  better  results  will  be 
obtained  by  dipping  the  hot  end  of  the  welding  rod 
into  the  flux  whenever  the  work  needs  it.  Suffi- 


56  WELDING 

cient  powder  will  stick  on  the  end  of  the  rod  for  all 
)  purposes,  and  with  some  fluxes  too  much  will  adhere. 
Care  should  always  be  used  to  avoid  the  application 
of  excessive  flux,  as  this  is  usually  worse  than  using 
too  little. 

SUPPLIES  AND  FIXTURES 

Goggles. — The  oxy-acetylene  torch  should  not  be 
used  without  the  protection  to  the  eyes  afforded  by 
goggles.  These  not  only  relieve  unnecessary  strain, 
but  make  it  much  easier  to  watch  the  exact  progress 
of  the  work  with  the  molten  metal  The  difficulty  of 
protecting  the  sight  while  welding  is  even  greater 
than  when  cutting  metal  with  the  torch. 

Acetylene  gives  a  light  which  is  nearest  to  sunlight 
of  any  artificial  illuminant.  But  for  the  fact  that 
this  gas  light  gives  a  little  more  green  and  less  blue 
in  its  composition,  it  would  be  the  same  in  quality 
and  practically  the  same  in  intensity.  This  light 
from  the  gas  is  almost  abseqt  during  welding,  being 
lost  with  the  addition  of  the)  extra  oxygen  needed  to 
produce  the  welding  heat.  *  The  light  that  is  dan- 
gerous comes  from  the  molten  metal  which  flows 
under  the  torch  at  a  bright  white  heat. 

Goggles  for  protection  against  this  light  and  the 
heat  that  goes  with  it  may  be  secured  in  various 
tints,  the  darker  glass  being  for  welding  and  the 
lighter  for  cutting.  Those  having  frames  in  which 
the  metal  parts  do  not  touch  the  flesh  directly  are 
most  desirable  because  of  the  high  temperature 
reached  by  these  parts. 

Gloves. — While  not  as  necessary  as  are  the  goggles, 
gloves  are  a  convenience  in  many  cases.  Those  in 
which  leather  touches  the  hands  directly  are  really 


OXY-ACETYLENE   WELDING  AND  CUTTING  MATERIALS  57 

of  little  value  as  the  heat  that  protection  is  desired 
against  makes  the  leather  so  hot  that  nothing  is  gained 
in  comfort.  Gloves  are  made  with  asbestos  cloth, 
which  are  not  open  to  this  objection  in  so  great  a 
degree. 


Figure  9. — Frame  for  Welding  Stand 

Tables  and  Stands. — Tables  for  holding  work  while 
being  welded  (Figure  9)  are  usually  made  from 
lengths  of  angle  steel  welded  together.  The  top  should 
be  rectangular,  about  two  feet  wide  and  two  and  one- 
half  feet  long.  The  legs  should  support  the  working 
surface  at  a  height  of  thirty-two  to  thirty-six  inches 
from  the  floor.  Metal  lattice  work  may  be  fastened 
or  laid  in  the  top  framework  and  used  to  support  a 
layer  of  firebrick  bound  together  with  a  mixture  of 
one-third  cement  and  two-thirds  fireclay.  The  piece 
being  welded  is  braced  and  supported  on  this  table 
with  pieces  of  firebrick  so  that  it  will  remain  station- 
ary during  the  operation. 


58  WELDING 

Holders  for  supporting  the  tanks  of  gas  may  be 
made  or  purchased  in  forms  that  rest  directly  on  the 
floor  or  that  are  mounted  on  wheels.  These  holders 
are  quite  useful  where  the  floor  or  ground  is  very 
uneven. 

Hose. — All  permanent  lines  from  tanks  and  gener- 
ators to  the  torches  are  made  with  piping  rigidly  sup- 
ported, but  the  short  distance  from  the  end  of  the 
pipe  line  to  the  torch  itself  is  completed  with  a  flexi- 
ble hose  so  that  the  operator  may  be  free  in  his  move- 
ments while  welding.  An  accident  through  which  the 
gases  mix  in  the  hose  and  are  ignited  will  burst  this 
part  of  the  equipment,  with  more  or  less  painful  re- 
sults to  the  person  handling  it.  For  that  reason  it  is 
well  to  use  hose  with  great  enough  strength  to  with- 
stand excessive  pressure. 

A  poor  grade  of  hose  will  also  break  down  inside 
and  clog  the  flow  of  gas,  both  through  itself  and 
through  the  parts  of  the  torch.  To  avoid  outside  dam- 
age and  cuts  this  hose  is  sometimes  encased  with 
coiled  sheet  metal.  Hose  may  be  secured  with  a  burst- 
ing strength  of  more  than  1,000  pounds  to  the  square 
inch.  Many  operators  prefer  to  distinguish  between 
the  oxygen  and  acetylene  lines  by  their  color  and  to 
allow  this,  red  is  used  for  the  oxygen,  and  bla£k_Jor 
acetylene. 

Other  Materials. — Sheet  asbestos  and  asbestos  fibre 
in  flakes  are  used  to  cover  parts  of  the  work  while  pre- 
paring them  for  welding  and  during  the  operation 
kself.  The  flakes  and  small  pieces  that  become  de- 
tached from  the  large  sheets  are  thrown  into  a  bin 
where  the  completed  small  work  is  placed  to  allow 
slow  and  even  cooling  while  protected  by  the  asbestos. 

Asbestos  fibre  and  also  ordinary  fireclay  are  often 


OXY-ACETYLENE   WELDING  AND   CUTTING  MATERIALS  59 

used  to  make  a  backing  or  mould  into  a  form  that 
may  be  placed  behind  aluminum  and  some  other 
metals  that  flow  at  a  low  heat  and  which  are  accord- 
ingly difficult  to  handle  under  ordinary  methods. 
This  forms  a  solid  mould  into  which  the  metal  is  prac- 
tically cast  as  melted  by  the  torch  so  that  the  desired 
shape  is  secured  without  danger  of  the  walls  of  metal 
breaking  through  and  flowing  away. 

Carbon  blocks  and  rods  are  made  in  various  shapes 
and  sizes  so  that  they  may  be -used  to  fill  threaded 
holes  and  other  places  that  it  is  desired  to  protect 
during  welding.  These  may  be  secured  in  rods  of 
various  diameters  up  to  one  inch  and  in  blocks  of 
several  different  dimensions. 


CHAPTER  III 
ACETYLENE  GENERATORS 

Acetylene  generators  used  for  producing  the  gas 
from  the  action  of  water  on  calcium  carbide  are  di- 
vided into  three  principal  classes  according  to  the 
pressure  under  which  they  operate. 

Low  pressure  generators  are  designed  to  operate  at 
one  pound  or  less  per  square  inch.  Medium  pressure 
systems  deliver  the  gas  at  not  to  exceed  fifteen  pounds 
to  the  square  inch  while  high  pressure  types  furnish 
gas  above  fifteen  pounds  per  square  inch.  High 
pressure  systems  are  almost  unknown  in  this  country, 
the  medium  pressure  type  being  often  referred  to  as 
"high  pressure." 

Another  important  distinction  is  formed  by  the 
method  of  bringing  the  carbide  and  water  together. 
The  majority  of  those  now  in  use  operate  by  drop- 
ping small  quantities  of  carbide  into  a  large  volume 
of  water,  allowing  the  generated  gas  to  bubble  up 
through  the  water  before  being  collected  above  the 
surface.  This  type  is  known  as  the  "carbide  to 
water "  generator. 

A  less  used  type  brings  a  measured  and  small  quan- 
tity of  water  to  a  comparatively  large  body  of  the 
carbide,  the  gas  being  formed  and  collected  from 
the  chamber  in  which  the  action  takes  place.  This 
is  called  the  "water  to  carbide77  type.  Another  way 
of  expressing  the  difference  in  feed  is  that  of  desig- 
nating the  two  types  as  "carbide  feed'7  for  the  former 
and  "water  feed77  for  the  latter. 

60 


ACETYLENE  GENERATORS  61 

A  further  division  of  the  carbide  to  water  ma- 
chines is  made  by  mentioning  the  exact  method  of 
feeding  the  carbide  One  type,  called  "gravity  feed" 
operates  by  allowing  the  carbide  to  escape  and  fall  by 
the  action  of  its  own  weight,  or  gravity;  the  other 
type,  called  "forced  feed,"  includes  a  separate  mech- 
anism driven  by  power  This  mechanism  feeds  defi- 
nite amounts  of  the  carbide  to  the  water  as  required 
by  the  demands  on  the  generator.  The  action  of 
either  feed  is  controlled  by  the  withdrawal  of  gas 
from  the  generator,  the  aim  being  to  supply  suffi- 
cient carbide  to  maintain  a  nearly  constant  supply. 

Generator  Requirements. — The  qualities  of  a  good 
generator  are  outlined  as  follows  :* 

It  must  allow  no  possibility  of  the  existence  of  an 
explosive  mixture  in  any  of  its  parts  at  any  time.  It 
is  not  enough  to  argue  that  a  mixture,  even  if  it  exists, 
cannot  be  exploded  unless  kindled.  It  is  necessary  to 
demand  that  a  dangerous  mixture  can  at  no  time  be 
formed,  even  if  the  machine  is  tampered  with  by  an 
ignorant  person.  The  perfect  machine  must  be  so 
constructed  that  it  shall  be  impossible  at  any  time, 
under  any  circumstances,  to  blow  it  up. 

It  must  insure  cool  generation.  Since  this  is  a  rela- 
tive term,  all  machines  being  heated  somewhat  dur- 
ing the  generation  of  gas,  this  amounts  to  saying  that 
a  machine  must  heat  but  little.  A  pound  of  carbide 
decomposed  by  water  develops  the  same  amount  of 
heat  under  all  circumstances,  but  that  heat  can  be 
allowed  to  increase  locally  to  a  high  point,  or  it  can 
be  equalized  by  water  so  that  no  part  of  the  material 
becomes  heated  enough  to  do  damage. 


r  See  Pond's  "Calcium  Carbide  and  Acetylene." 


62  WELDING 

It  must  be  well  constructed.  A  good  generator 
does  not  need,  perhaps,  to  be  ' '  built  like  a  watch, ' '  but 
it  should  be  solid,  substantial  and  of  good  material. 
It  should  be  built  for  service,  to  last  and  not  simply 
to  sell;  anything  short  of  this  is  to  be  avoided  as 
unsafe  and  unreliable. 

It  must  be  simple.  The  more  complicated  the  ma- 
chine the  sooner  it  will  get  out  of  order.  Understand 
your  generator.  Know  what  is  inside  of  it  and  be- 
ware of  an  apparatus,  however  attractive  its  exterior, 
whose  interior  is  filled  with  pipes  and  tubes,  valves 
and  diaphragms  whose  functions  you  do  not  per- 
fectly understand. 

It  should  be  capable  of  being  cleaned  and  re- 
charged and  of  receiving  all  other  necessary  atten- 
tion without  loss  of  gas,  both  for  economy 's  sake,  and 
more  particularly  to  avoid  danger  of  fire. 

It  should  require  little  attention.  All  machines 
have  to  be  emptied  and  recharged  periodically;  but 
the  more  this  process  is  simplified  and  the  more 
quickly  this  can  be  accomplished,  the  better. 

It  should  be  provided  with  a  suitable  indicator  to 
designate  how  low  the  charge  is  in  order  that  the 
refilling  may  be  done  in  good  season. 

It  should  completely  use  up  the  carbide,  generat- 
ing the  maximum  amount  of  gas. 

Overheating. — A  large  amount  of  heat  is  liberated 
when  acetylene  gas  is  formed  from  the  union  of  cal- 
cium carbide  and  water.  Overheating  during  this 
process,  that  is  to  say,  an  intense  local  heat  rather 
than  a  large  amount  of  heat  well  distributed,  brings 
about  the  phenomenon  of  polymerization,  converting 
the  gas,  or  part  of  it,  into  oily  matters,  which  can  do 
nothing  but  harm.  This  tarry  mass  coming  through 


ACETYLENE  GENERATORS  63 

the  small  openings  in  the  torches  causes  them  to  be- 
come partly  closed  and  alters  the  proportions  of  the 
gases  to  the  detriment  of  the  welding  flame.  The  only 
remedy  for  this  trouble  is  to  avoid  its  cause  and 
secure  cool  generation. 

Overheating  can  be  detected  by  the  appearance  of 
the  sludge  remaining  after  the  gas  has  been  made. 
Discoloration,  yellow  or  brown,  shows  that  there  has 
been  trouble  in  this  direction  and  the  resultant  effects 
at  the  torches  may  be  looked  for.  The  abundance  of 
water  in  the  carbide  to  water  machines  effects  this 
cooling  naturally  and  is  a  characteristic  of  well  de- 
signed machines  of  this  class.  It  has  been  found  best 
and  has  practically  become  a  fundamental  rule  of 
generation  that  a  gallon  of  water  must  be  provided 
for  each  pound  of  carbide  placed  in  the  generator. 
With  this  ratio  and  a  generator  large  enough  for 
the  number  of  torches  to  be  supplied,  little  trouble 
need  be  looked  for  with  overheating. 

Water  to  Carbide  Generators. — It  is,  of  course, 
much  easier  to  obtain  a  measured  and  regular  flow  of 
water  than  to  obtain  such  a  flow  of  any  solid  sub- 
stance, especially  when  the  solid  substance  is  in  the 
form  of  lumps,  as  is  carbide  This  fact  led  to  the  use 
of  a  great  many  water-feed  generators  for  all  classes 
of  work,  and  this  type  is  still  in  common  use  for  the 
small  portable  machines,  such,  for  instance,  as  those 
used  on  motor  cars  for  the  lamps.  The  water-feed 
machine  is  not,  however,  favored  for  welding  plants, 
as  is  the  carbide  feed,  in  spite  of  the  greater  difficul- 
ties attending  the  handling  of  the  solid  material. 

A  water-feed  generator  is  made  up  of  the  gas  pro- 
ducing part  and  a  holder  for  the  acetylene  after  it 
is  made.  The  carbide  is  held  in  a  tray  formed  of  a 


64  WELDING 

number  of  small  compartments  so  that  the  charge 
in  each  compartment  is  nearly  equal  to  that  in  each 
of  the  others.  The  water  is  allowed  to  flow  into  one 
of  these  compartments  in  a  volume  sufficient  to  pro- 
duce the  desired  amount  of  gas  and  the  carbide  is 
completely  used  from  this  one  division.  The  water 
then  floods  the  first  compartment  and  finally  over- 
flows into  the  next  one,  where  the  same  process  is 
repeated.  After  using  the  carbide  in  this  division, 
it  is  flooded  in  turn  and  the  water  passing  on  to 
those  next  in  order,  uses  the  entire  charge  of  the 
whole  tray. 

These  generators  are  charged  with  the  larger  sizes 
of  carbide  and  are  easily  taken  care  of.  The  residue 
is  removed  in  the  tray  and  emptied,  making  the  gen- 
erator ready  for  a  fresh  supply  of  carbide. 

Carbide  to  Water  Generators. — This  type  also  is 
made  up  of  two  principal  parts,  the  generating  cham- 
ber and  a  gas  holder,  the  holder  being  part  of  the 
generating  chamber  or  a  separate  device.  The  gen- 
erator (Figure  10)  contains  a  hopper  to  receive  the 
charge  of  carbide  and  is  fitted  with  the  feeding  mech- 
anism to  drop  the  proper  amount  of  carbide  into  the 
water  as  required  by  the  demands  of  the  torches.  The 
charge  of  carbide  is  of  one  of  the  smaller  sizes, 
usually  "nut"  or  "quarter." 

Feed  Mechanisms. — The  device  for  dropping  the 
carbide  into  the  water  is  the  only  part  of  the  machine 
that  is  at  all  complicated.  This  complication  is 
brought  about  by  the  necessity  of  controlling  the 
mass  of  carbide  so  that  it  can  never  be  discharged 
into  the  water  at  an  excessive  rate,  feeding  it  at  a 
regular  rate  and  in  definite  amounts,  feeding  it  posi- 
tively whenever  required  and  shutting  off  the  feed 


ACETYLENE  GENERATORS 


65 


just  as  positively   when   the  supply   of  gas  in   the 
holder  is  enough  for  the  immediate  needs. 

The  charge  of  carbide  is  unavoidably  acted  upon 
by  the  water  vapor  in  the  generator  and  will  in  time 


til 

n  «••••*  O 


become  more  or  less  pasty  and  sticky.  This  is  more 
noticeable  if  the  generator  stands  idle  for  a  consider- 
able length  of  time  This  condition  imposes  another 
duty  on  the  feeding  mechanism ;  that  is,  the  necessity 
of  self-cleaning  so  that  the  carbide,  no  matter  in  what 


66  WELDING 

condition,  cannot  prevent  the  positive  action  of  this 
part  of  the  device,  especially  so  that  it  cannot  prevent 
the  supply  from  being  stopped  at  the  proper  time. 

The  gas  holder  is  usually  made  in  the  bell  form 
so  that  the  upper  portion  rises  and  falls  with  the 
addition  to  or  withdrawal  from  the  supply  of  gas 
in  the  holder.  The  rise  and  fall  of  this  bell  is  often 
used  to  control  the  feed  mechanism  because  this 
movement  indicates  positively  whether  enough  gas 
has  been  made  or  that  more  is  required.  As  the  bell 
lowers  it  sets  the  feed  mechanism  'in  motion,  and 
when  the  gas  passing  into  the  holder  has  raised  the 
bell  a  sufficient  distance,  the  movement  causes  the 
feed  mechanism  to  stop  the  fall  of  carbide  into  the 
water.  In  practice,  the  movement  of  this  part  of  the 
holder  is  held  within  very  narrow  limits. 

Gas  Holders. — No  matter  how1  close  the  adjustment 
of  the  feeding  device,  there  will  always  be  a  slight 
amount  of  gas  made  after  the  fall  of  carbide  is 
stopped,  this  being  caused  by  the  evolution  of  gas 
from  the  carbide  with  which  water  is  already  in  con- 
tact. This  action  is  called  " after  generation"  and 
the  gas  holder  in  any  type  of  generator  must  provide 
sufficient  capacity  to  accommodate  this  excess  gas. 
As  a  general  rule  the  water  -to  carbide  generator 
requires  a  larger  gas  holder  than  the  carbide  to  water 
type  because  of  the  greater  amount  of  carbide  being 
acted  upon  by  the  water  at  any  one  time,  also  be- 
cause the  surface  of  carbide  presented  to  the  moist 
air  within  the  generating  chamber  is  greater  with 
this  type. 

Freezing. — Because  of  the  rather  large  body  of 
water  contained  in  any  type  of  generator,  there  is 
always  danger  of  its  freezing  and  rendering  the 


ACETYLENE  GENERATORS  67 

device  inoperative  unless  placed  in  a  temperature 
above  the  freezing  point  of  the  water.  It  is,  of 
course,  dangerous  and  against  the  insurarce  rules  to 
place  a  generator  in  the  same  room  with  a  fire  of  any 
kind,  but  the  room  may  be  heated  by  steam  or  hot 
water  coils  from  a  furnace  in  another  building  or 
in  another  part  of  the  same  building. 

When  the  generator  is  housed  in  a  separate  struc- 
ture the  walls  should  be  made  of  materials  or  con- 
struction that  prevents  the  passage  of  heat  or  cold 
through  them  to  any  great  extent.  This  may  be 
accomplished  by  the  use  of  hollow  tile  or  concrete 
blocks  or  by  any  other  form  of  double  wall  providing 
air  spaces  between  the  outer  and  inner  facings.  The 
space  between  the  parts  of  the  wall  may  be  filled  with 
materials  that  further  retard  the  loss  of  heat  if  this 
is  necessary  under  the  conditions  prevailing. 

Residue  From  Generators. — The  sludge  remaining 
in  the  carbide  to  water  generator  may  be  drawn  off 
into  the  sewer  if  the  piping  is  run  at  a  slant  great 
enough  to  give  a  fall  that  carries  the  whole  quantity, 
both  water  and  ash,  away  without  allowing  settling 
and  consequent  clogging.  Generators  are  provided 
with  agitators  which  are  operated  to  stir  the  ash  up 
with  the  water  so  that  the  whole  mass  is  carried  off 
when  the  drain  cock  is  opened. 

If  sewer  connections  cannot  be  made  in  such  a  way 
that  the  ash  is  entirely  carried  away,  it  is  best  to 
run  the  liquid  mass  into  a  settling  basin  outside  of 
the  building.  This  should  be  in  the  form  of  a  shallow 
pit  which  will  allow  the  water  to  pass  off  by  soaking 
into  the  ground  and  by  evaporation,  leaving  the 
comparatively  dry  ash  in  the  pit.  This  ash  which 
remains  is  essentially  slaked  lime  and  can  often  be 


68  WELDING 

disposed  of  to  more  or  less  advantage  to  be  used  in 
mortar,  whitewash,  marking  paths  and  any  other  use 
for  which  slaked  lime  is  suited.  The  disposition  of 
the  ash  depends  entirely  on  local  conditions.  An 
average  analysis  of  this  ash  is  as  follows : 

Sand 1.10  per  cent. 

Carbon  2.72 

Oxide  of  iron  and  alumina. .  2.77 

Lime 64.06 

Water  and  carbonic  acid.  . .  29.35        " 

Toooo 

GENERATOR    CONSTRUCTION 

The  water  for  generating  purposes  is  carried  in  the 
large  tank-like  compartment  directly  below  the  car- 
bide chamber.  See  Figure  11.  This  water  compart- 
ment is  filled  through  a  pipe  of  such  a  height  that 
the  water  level  cannot  be  brought  above  the  proper 
point  or  else  the  water  compartment  is  provided  with 
a  drain  connection  which  accomplishes  this  same  re- 
sult by  allowing  an  excess  to  flow  away. 

The  quantity  of  water  depends  on  the  capacity  of 
the  generator  inasmuch  as  there  must  be  one  gallon 
for  each  pound  of  carbide  required.  The  generator 
should  be  of  sufficient  capacity  to  furnish  gas  under 
working  conditions  from  one  charge  of  carbide  to  all 
torches  installed  for  at  least  five  hours  continuous 
use. 

After  calculating  the  withdrawal  of  the  whole 
number  of  torches  according  to  the  work  they  are 
to  do  for  this  period  of  five  hours  the  proper  gen- 


ACETYLENE  GENERATORS  69 

erator  capacity  may  be  found  on  the  basis  of  one 
cubic  foot  of  gas  per  hour  for  each  pound  of  carbide. 
Thus  if  the  torches  were  to  use  sixty  cubic  feet  of 
gas  per  hour,  five  hours  would  call  for  three  hundred 
cubic  feet  and  a  three  hundred  pound  generator 
should  be  installed.  Generators  are  rated  according 
to  their  carbide  capacity  in  pounds. 

Charging. — The  carbide  capacity  of  the  generator 
should  be  great  enough  to  furnish  a  continuous  sup- 
ply of  gas  for  the  maximum  operating  time,  basing 
the  quantity  of  gas  generated  on  four  and  one-half 
cubic  feet  from  each  pound  of  lump  carbide  and  on 
four  cubic  feet  from  each  pound  of  quarter,  inter- 
mediate sizes  being  in  proportion. 

Generators  are  built  in  such  a  way  that  it  is  impos- 
sible for  the-  acetylene  to  escape  from  the  gas  holding: 
compartment  during  the  recharging  process.  This 
is  accomplished  (1)  by  connecting  the  water  inlet 
pipe  opening  with  a  shut  off  valve  in  such  a  way 
that  the  inlet  cannot  be  uncovered  or  opened  without 
first  closing  the  shut  off  valve  with  the  same  move- 
ment of  the  operator;  (2)  by  incorporating  an  auto- 
matic or  hydraulic  one-way  valve  so  that  this  valve 
closes  and  acts  as  a  check  when  the  gas  attempts  to 
flow  from  the  holder  back  to  the  generating  chamber, 
or  by  any  other  means  that  will  positively  accomplish 
this  result. 

In  generators  having  no  separate  gas  holding 
chamber  but  carrying  the  supply  in  the  same  com- 
partment in  which  it  is  generated,  the  gas  contained 
under  pressure  is  allowed  to  escape  through  vent 
pipes  into  the  outside  air  before  recharging  with 
carbide.  As  in  the  former  case,  the  parts  are  so 
interlocked  that  it  is  impossible  to  introduce  carbide 


70  WELDING 

or  water  without  first  allowing  the  escape  of  the  gas 
in  the  generator. 

It  is  required  by  the  insurance  rules  that  the  entire 
change  of  carbide  while  in  the  generator  be  held  in 
such  a  way  that  it  may  be  entirely  removed  without 
difficulty  in  case  the  necessity  should  arise. 

Generators  should  be  cleaned  and  recharged  at 
regular  stated  intervals.  This  work  should  be  done 
during  daylight  hours  only  and  likewise  all  repairs 
should  be  made  at  such  a  time  that  artificial  light 
is  not  needed.  Where  it  is  absolutely  necessary  to 
use  artificial  light  it  should  be  provided  only  by 
incandescent  electric  lamps  enclosed  in  gas  tight 
globes. 

In  charging  generating  chambers  the  old  ash  and 
all  residue  must  first  be  cleaned  out  and  the  operator 
should  be  sure  that  no  drain  or  other  pipe  has  become 
clogged.  The  generator  should  then  be  filled  with 
the  required  amount  of  water.  In  charging  carbide 
feed  machines  be  careful  not  to  place  less  than 
a  gallon  of  water  in  the  water  compartment  for  each 
pound  of  carbide  to  be  used  and  the  water  must  be 
brought  to,  but  not  above,  the  proper  level  as  indi- 
cated by  the  mark  or  the  maker's  instructions.  The 
generating  chamber  must  be  filled  with  the  proper 
amount  of  water  before  any  attempt  is  made  to  place 
the  carbide  in  its  holder.  This  rule  must  always  be 
followed.  It  is  also  necessary  that  all  automatic  water 
seals  and  valves,  as  well  as  any  other  water  tanks, 
be  filled  with  clean  water  at  this  time. 

Never  recharge  with  carbide  without  first  cleaning 
the  generating  chamber  and  completely  refilling  with 
clean  water.  Never  test  the  generator  or  piping  for 
leaks  with  any  flame,  and  never  apply  flame  to  any 


ACETYLENE  GENERATORS  71 

open  pipe  or  at  any  point  other  than  the  torch,  and 
only  to  the  torch  after  it  has  a  welding  or  cutting 
nozzle  attached.  Never  use  a  lighted  match,  lamp, 
candle,  lantern,  cigar  or  any  open  flame  near  a  gen- 
erator. Failure  to  observe  these  precautions  is  liable 
to  endanger  life  and  property. 

Operation  and  Care  of  Generators. — The  following 
instructions  apply  especially  to  the  Davis  Bournon- 
ville  pressure  generator,  illustrated  in  Figure  11. 
The  motor  feed  mechanism  is  illustrated  in  Figure  12. 

Before  filling  the  machine,,  the  cover  should  be 
removed  and  the  hopper  taken  out  and  examined  to 
see  that  the  feeding  disc  revolves  freely;  that  no 
chains  have  been  displaced  or  broken,  and  that  the 
carbide  displacer  itself  hangs  barely  free^of  the  feed- 
ing disc  when  it  is  revolved.  After  replacing  the 
cover,  replace  the  bolts  and  tighten  them  equally,  a 
little  at  a  time  all  around  the  circumference  of  the 
cover — not  screwing  tight  in  one  place  only.  Do  not 
screw  the  cover  down  any  more  than  is  necessary  to 
make  a  tight  fit. 

To  charge  the  generator,  proceed  as  follows :  Open 
the  vent  valve  by  turning  the  handle  which  extends 
over  the  filling  tube  until  it  stands  at  a  right  angle 
with  the  generator.  Open  the  valve  in  the  water 
filling  pipe,  and  through  this  fill  with  water  until  it 
runs  out  of  the  overflow  pipe  of  the  drainage  cham- 
ber ;  then  close  the  valve  in  the  water  filling  pipe  and 
vent  valve.  Remove  the  carbide  filling  plugs  and  fill 
the  hopper  with  li/4"x%"  carbide  ("nut"  size). 
Then  replace  the  plugs  and  the  safety-locking  lever 
chains.  Now  rewind  the  motor  weight.  Run  the 
pressure  up  to  about  five  pounds  by  raising  the  con- 
trolling diaphragm  valve  lever  by  hand  (Figure  12, 


72 


WELDING 


lever  marked  E).  Then  raise  the  blow-off  lever, 
allowing  the  gas  to  blow  off  until  the  gauge  shows 
about  two  pounds;  this  to  clear  the  generator  of  air 
mixture.  Then  run  the  pressure  up  to  about  eight 


Figure  11. — Pressure  Generator  (Davis  Bournonville).  A,  Feed 
motor  weight;  B,  Carbide  feed  motor;  C,  Motor  control  diaphragm; 
D,  Carbide  hopper  ;  E,  Carbide  feed  disc ;  F,  Overflow  pipe  ;  G,  Over- 
flow pipe  seal ;  H,  Overflow  pipe  valve  ;  J,  Filling  funnel ;  K,  Hydraulic 
valve  ;  L,  Expansion  chamber ;  M ,  Escape  pipe  ;  N,  Feed  pipe ;  O, 
Agitator  for  residuum  ;  P3  Residuum  valve  ;  Q,  Water  level 


ACETYLENE  GENERATORS  73 

pounds  by  raising  the  controlling  valve  lever  E,  or 
until  this  controlling  lever  rests  against  the  upper 
wing  of  the  fan  governor,  and  prevents  operation 
of  the  feed  motor.  After  this  is  done,  ,the  motor  will 
operate  automatically  as  the  gas  is  consumed. 

Should  the  pressure  rise  much  above  the  blow-off 
point,  the  safety  controlling  diaphragm  valve  will 
operate  and  throw  the  safety  clutch  in  interference 


Figure  12. — Feed  Mechanism  of  Pressure  Generator 

and  thus  stop  the  motor.  This  interference  clutch 
will  then  have  to  be  returned  to  its  former  position 
before  the  motor  will  operate,  but  cannot  be  replaced 
before  the  pressure  has  been  reduced  below  the  blow- 
off  point. 

The  parts  of  the  feed  mechanism  illustrated  in 
Figure  12  are  as  follows :  A,  motor  drum  for  weight 
cable.  B,  carbide  filling  plugs.  C,  chains  for  con- 
necting safety  locking  lever  of  motor  to  pins  on  the- 
top  of  the  carbide  plugs.  D,  interference  clutch  of 
motor.  E,  lever  on  feed  controlling  diaphragm  valve. 


74  WELDING 

F,  lever  of  interference  controlling  diaphragm  valve 
that  operates  interference  clutch.  G,  feed  controlling 
diaphragm  valve.  H,  diaphragm  valve  controlling 
operation  of  interference  clutch.  I,  interference  pin 
to  engage  emergency  clutch.  J,  main  shaft  driving 
carbide  feeding  disc.  Y,  safety  locking  lever. 

Recharging  Generator. — Turn  the  agitator  handle 
rapidly  for  several  revolutions,  and  then  open  the 
residuum  valve,  having  five  or  six  pounds  gas  pres- 
sure on  the  machine.  If  the  carbide  charge  has  been 
exhausted  and  the  motor  has  stopped,  there  is  gen- 
erally enough  carbide  remaining  in  the  feeding  disc 
that  can  be  shaken  off,  and  fed  by  running  the  motor 
to  obtain  some  pressure  in  the  generator.  The  desir- 
ability of  discharging  the  residuum  with  some  gas 
pressure  is  because  the  pressure  facilitates  the  dis- 
charge and  at  the  same  time  keeps  the  generator  full 
of  gas,  preventing  air  mixture  to  a  great  extent.  As 
soon  as  the  pressure  is  relieved  by  the  withdrawal  of 
the  residuum,  the  vent  valve  should  be  opened,  as  if 
the  pressure  is  maintained  until  all  of  the  residuum 
is  discharged  gas  would  escape  through  the  discharge 
valve. 

Having  opened  the  vent  pipe  valve  and  relieved 
the  pressure,  open  the  valve  in  the  water  filling  tube. 
Close  the  residuum  valve,  then  run  in  several  gallons 
of  water  and  revolve  the  agitator,  after  which  draw 
out  the  remaining .  residuum ;  then  again  close  the 
residuum  valve  and  pour  in  water  until  it  discharges 
from  the  overflow  pipe  of  the  drainage  chamber.  It 
is  desirable  in  filling  the  generator  to  pour  the  wTater 
in  rapidly  enough  to  keep  the  filling  pipe  full  of 
water,  so  that  air  will  not  pass  in  at  the  same  time. 

After   the    generator    is    cleaned    and    filled   with 


ACETYLENE  GENERATORS  75 

water,  fill  with  carbide  and  proceed  in  the  same  man- 
ner as  when  first  charging. 

Carbide  Feed  Mechanism. — Any  form  of  carbide 
to  water  machine  should  be  so  designed  that  the  car- 
bide never  falls  directly  from  its  -  holder  into  the 
water,  but  so  that  it  must  take  a  more  or  less  cir- 
cuitous path.  This  should  be  true,  no  matter  what 
position  the  mechanism  is  in.  One  of  the  commonest 
types  of  forced  feed  machine  carries  the  carbide  in 
a  hopper  with  slanting  sides,  this  hopper  having  a 
large  opening  in  the  bottom  through  which  the  car- 
bide passes  to  a  revolving  circular  plate.  As  the 
pieces  of  carbide  work  out  toward  the  edge  of  the 
plate  under  the  influence  of  the  mass  behind  them, 
they  are  thrown  off  into  the  water  by  small  stationary 
fins  or  plows  which  are  in  such  a  position  that  they 
catch  the  pieces  nearest  the  edges  and  force  them 
off  as  the  plate  revolves.  This  arrangement,  while 
allowing  a  free  passage  for  the  carbide,  prevents  an 
excess  from  falling  should  the  machine  stop  in  any 
position. 

When,  as  is  usually  the  case,  the  feed  mechanism 
is  actuated  by  the  rise  or  fall  of  pressure  in  the 
generator  or  of  the  level  of  some  part  of  the  gas 
holder,  it  must  be  built  in  such  a  way  that  the  feed- 
ing remains  inoperative  as  long  as  the  filling  opening 
on  the  carbide  holder  remains  open. 

The  feed  of  carbide  should  always  be  shut  off  and 
controlled  so  that  under  no  condition  can  more  gas 
be  generated  than  could  be  cared  for  by  the  relief 
valve  provided.  It  is  necessary  also  to  have  the  feed 
mechanism  at  least  ten  inches  above  the  surface  of 
the  water  so  that  the  parts  will  never  become  clogged 
with  damp  lime  dust. 


76  WELDING 

Motor  Feed. — The  feed  mechanism  itself  is  usually 
operated  by  power  secured  from  a  slowly  falling 
weight  which,  through  a  cable,  revolves  a  drum.  To 
this  drum  is  attached  suitable  gearing  for  moving  the 
feed  parts  with  sufficient  power  and  in  the  way 
desired.  This  part,  called  the  motor,  is  controlled 
by  two  levers,  one  releasing  a  brake  and  allowing  the 
motor  to  operate  the  feed,  the  other  locking  the  gear- 
ing so  that  no  more  carbide  will  be  dropped  into  the 
water.  These  levers  are  moved  either  by  the  quantity 
of  gas  in  the  holder  or  by  the  pressure  of  the  gas, 
depending  on  the  type  of  machine. 

With  a  separate  gas  holder,  such  as  used  with  low 
pressure  systems,  the  levers  are  operated  by  the  rise 
and  fall  of  the  bell  of  the  holder  or  gasometer,  alter- 
nately starting  and  stopping  the  motor  as  the  bell 
falls  and  rises  again.  Medium  pressure  generators  are 
provided  with  a  diaphragm  to  control  the  feed  motor. 

This  diaphragm  is  carried  so  that  the  pressure 
within  the  generator  acts  on  one  side  while  a  spring, 
whose  tension  is  under  the  control  of  the  operator, 
acts  on  the  other  side.  The  diaphragm  is  connected 
to  the  brake  and  locking  device  on  the  motor  in 
such  a  way  that  increasing  the  tension  on  the  spring 
presses  the  diaphragm  and  moves  a  rod  that  releases 
the  brake  and  starts  the  feed.  The  gas  pressure, 
increasing  with  the  continuation  of  carbide  feed,  acts 
on  the  other  side  and  finally  overcomes  the  pressure 
of  the  spring  tension,  moving  the  control  rod  the 
other  way  and  stopping  the  motor  and  carbide  feed. 
This  spring  tension  is  adjusted  and  checked  with  the 
help  of  a  pressure  gauge  attached  to  the  generating 
chamber. 

Gravity  Feed. — This  type  of  feed  differs  from  the 


ACETYLENE  GENERATORS  77 

foregoing  in  that  the  carbide  is  simply  released  and 
is  allowed  to  fall  into  the  water  without  being  forced 
to  do  so.  Any  form  of  valve  that  is  sufficiently 
powerful  in  action  to  close  with  the  carbide  passing 
through  is  used  and  is  operated  by  the  power  secured 
from  the  rise  and  fall  of  the  gas  holder  bell.  When 
this  valve  is  first  opened  the  carbide  runs  into  the 
water  until  sufficient  pressure  and  volume  of  gas  is 
generated  to  raise  the  bell.  This  movement  operates 
the  arm  attached  to  the  carbide  shut  off  valve  and 
slowly  closes  it.  A  fall  of  the  bell  occasioned  by  gas 
being  withdrawn  again  opens  the  valve  and  more  gas 
is  generated. 

Mechanical  Feed. — The  previously  described  meth- 
ods of  feeding  carbide  to  the  water  have  all  been 
automatic  in  action  and  do  not  depend  on  the  oper- 
ator for  their  proper  action. 

Some  types  of  large  generating  plants  have  a 
power-driven  feed,  the  power  usually  being  from 
some  kind  of  motor  other  than  one  operated  by  a 
weight,  such  as  a  water  motor,  for  instance  This 
motor  is  started  and  stopped  by  the  operator  when, 
in  his  judgment,  more  gas  is  wanted  or  enough  has 
been  generated.  This  type  of  machine,  often  called 
a  "non-automatic  generator,"  is  suitable  for  large 
installations  and  is  attached  to  a  gas  holder  of  suffi- 
cient size  to  hold  a  day's  supply  of  acetylene.  The 
generator  can  then  be  operated  until  a  quantity  of 
gas  has  been  made  that  will  fill  the  large  holder,  or 
gasometer,  and  then  allowed  to  remain  idle  for  some 
time. 

Gas  Holders. — The  commonest  type  of  gas  con- 
tainer is  that  known  as  a  gasometer.  This  consists 
of  a  circular  tank  partly  filled  with  water,  into  which 


78  WELDING 

is  lowered  another  circular  tank,  inverted,  which  is 
made  enough  smaller  in 'diameter  than  the  first  one 
so  that  three-quarters  of  an  inch  is  left  between  them. 
This  upper  and  inverted  portion,  called  the  bell, 
receives  the  gas  from  the  generator  and  rises  or  falls 
in  the  bath  of  water  provided  in  the  lower  tank  as 
a  greater  or  less  amount  of  gas  is  contained  in  it. 

These  holders  are  made  large  enough  so  that  they 
will  provide  a  means  of  caring  for  any  after  genera- 
tion and  so  that  they  maintain  a  steady  and  even 
flow.  The  generator,  however,  must  be  of  a  capacity 
great  enough  so  that  the  gas  holder  will  not  be  drawn 
on  for  part  of  the  supply  with  all  torches  in  opera- 
tion. That  is,  the  holder  must  not  be  depended  on 
for  a  reserve  supply. 

The  bell  of  the  holder  is  made  so  that  when  full 
of  gas  its  lower  edge  is  still  under  a  depth  of  at 
least  nine  inches  of  water  in  the  lower  tank.  Any 
further  rise  beyond  this  point  should  always  release 
the  gas,  or  at  least  part  of  it,  to  the  escape  pipe  so 
that  the  gas  will  under  no  circumstances  be  forced 
into  the  room  from  between  the  bell  and  tank.  The 
bell  is  guided  in  its  rise  and  fall  by  vertical  rods  so 
that  it  will  not  wedge  at  any  point  in  its  travel. 

A  condensing  chamber  to  receive  the  water  which 
condenses  from  the  acetylene  gas  in  the  holder  is 
usually  placed  under  this  part  and  is  provided  with 
a  drain  so  that  this  water  of  condensation  may  be 
easily  removed. 

Filtering.  —  A  small  chamber  containing  some 
closely  packed  but  porous  material  such  as  felt  is 
placed  in  the  pipe  leading  to  the  torch  lines.  As 
the  acetylene  gas  passes  through  this  filter  the  parti- 
cles of  lime  dust  and  other  impurities  are  extracted 


ACETYLENE  GENERATORS 


79 


from  it  so  that  danger  of  clogging  the  torch  openings 
is  avoided  a's  much  as  possible. 

The  gas  is  also  filtered  to  a  large  extent  by  its 
passage  through  the  water  in  the  generating  chamber, 
this  filtering  or  "scrubbing"  often  being  facilitated 
by  the  form  of  piping  through  which  the  gas  must 
pass  from  the  generating  chamber  into  the  holder. 
If  the  gas  passes  out  of  a  number  of  small  openings 
when  going  into  the  holder  the  small  bubbles  give 
a  better  washing  than  large  ones  would. 

Piping. — Connections  from  generators  to  service 
pipes  should  preferably  be  made  with  right  and  left 
couplings  or  long  thread  nipples  with  lock  nuts.  If 
unions  are  used,  they  should  be  of  a  type. that  does 
not  require  gaskets.  The  piping  should  be  carried 
and  supported  so  that  any  moisture  condensing  in 
the  lines  will  drain  back  toward  the  generator  and 
where  low  points  occur  they  should  be  drained 
through  tees  leading  into  drip  cups  which  are  per- 
manently closed  with  screw  caps  or  plugs.  No  pet 
cocks  should  be  used  for  this  purpose. 

For  the  feed  pipes  to  the  torch  lines  the  following 
pipe  sizes  are  recommended. 
%  inch  pipe.     26  feet  long. 
3/2  inch  pipe.     30  feet  long. 
%  inch  pipe.      50  feet  long. 

1  inch  pipe.     70  feet  long. 
1%  inch  pipe.   100  feet  long. 
iy2  inch  pipe.   150  feet  long. 

2  inch  pipe.   200  feet  long.   125  cubic  feet  per  hour. 
2y2  inch  pipe.   300  feet  long.    190  cubic  feet  per  hour. 

3  inch  pipe.   450  feet  long.    335  cubic  feet  per  hour. 
When  drainage  is  possible  into  a  sewer,  the  gen- 
erator should  not  be  connected  directly  into  the  sewer 


2  cubic  feet  per  hour. 

4  cubic  feet  per  hour. 
15  cubic  feet  per  hour. 
27  cubic  feet  per  hour. 
50  cubic  feet  per  hour. 
65  cubic  feet  per  hour. 


80  WELDING 

but  should  first  discharge  into  an  open  receptacle, 
which  may  in  turn  be  connected  to  the  sewer. 

No  valves  or  pet  cocks  should  open  into  the  gen- 
erator room  or  any  other  room  when  it  would  be 
possible,  by  opening  them  for  draining  purposes,  to 
allow  any  escape  of  gas.  Any  condensation  must 
be  removed  without  the  use  of  valves  or  other  work- 
ing parts,  being  drained  into  closed  receptacles.  It 
should  be  needless  to  say  that  all  the  piping  for  gas 
must  be  perfectly  tight  at  every  point  in  its  length. 

Safety  Devices. — Good  generators  are  built  in  such 
a  way  that  the  operator  must  follow  the  proper  order 
of  operation  in  charging  and  cleaning  as  well  as  in 
all  other  necessary  care.  It  has  been  mentioned  that 
the  gas  pressure  is  released  or  shut  off  before  it  is 
possible  to  fill  the  water  compartment,  and  this  same 
idea  is  carried  further  in  making  the  generator  inop- 
erative and  free  from  gas  pressure  before  opening 
the  residue  drain  of  the  carbide  filling  opening  on 
top  of  the  hopper.  Some  machines  are  made  so  that 
they  automatically  cease  to  generate  should  there  be 
a  sudden  and  abnormal  withdrawal  of  gas  such  as 
would  be  caused  by  a  bad  leak.  This  method  of 
adding  safety  by  automatic  means  and  interlocking 
parts  may  be  carried  to  any  extent  that  seems  desir- 
able or  necessary  to  the  maker. 

All 'generators  should  be  provided  with  escape  or 
relief  pipes  of  large  size  which  lead  to  the  open  air. 
These  pipes  are  carried  so  that  condensation  will 
drain  back  toward  the  generator  and  after  being  led 
out  of  the  building  to  a  point  at  least  twelve  feet 
above  ground,  they  end  in  a  protecting  hood  so  that 
no  rain  or  solid  matter  can  find  its  way  into  them. 
Any  escape  of  gas  which  might  ordinarily  pass  into 


ACETYLENE  GENERATORS  81 

the  generator  room  is  led  into  these  escape  pipes,  all 
parts  of  the  system  being  connected  with  the  pipe 
so  that  the  gas  will  find  this  way  out. 

Safety  blow  off  valves  are  provided  so  that  any 
excess  gas  which  cannot  be  contained  by  the  gas 
holder  may  be  allowed  to  escape  without  causing  an 
undue  rise  in  pressure.  This  valve  also  allows  the 
escape  of  pressure  above  that  for  which  the  generator 
was  designed.  Gas  released  in  this  way  passes  into 
the  escape  pipe  just  described. 

Inasmuch  as  the  pressure  of  the  oxygen  is  much 
greater  than  that  of  the  acetylene  when  used  in  the 
torch,  it  will  be  seen  that  anything  that  caused  the 
torch  outlet  to  become  closed  would  allow  the  oxygen 
to  force  the  acetylene  back  into  the  generator  and 
the  oxygen  would  follow  it,  making  a  very  explosive 
mixture.  This  return  of  the  gas  is  prevented  by  a 
hydraulic  safety  valve  or  back  pressure  valve,  as  it  is 
often  called. 

Mechanical  check  valves  have  been  found  unsuit- 
able for  this  use  and  those  which  employ  water  as  a 
seal  are  now  required  by  the  insurance  rules.  The 
valve  itself  (Figure  13)  consists  of  a  large  cylinder 
containing  water  to  a  certain  depth,  which  is  indi- 
cated on  the  valve  body.  Two  pipes  come  into  the 
upper  end  of  this  cylinder  and  lead  down  into  the 
water,  one  being  longer  than  the  other.  The  shorter 
pipe  leads  to  the  escape  pipe  mentioned  above,  while 
the  longer  one  comes  from  the  generator.  The  upper 
end  of  the  cylinder  has  an  opening  to  which  is  at- 
tached the  pipe  leading  to  the  torches. 

The  gas  coming  from  the  generator  through  the 
longer  pipe  passes  out  of  the  lower  end  of  the  pipe 
which  is  under  water  and  bubbles  up  through  the 


WELDING 


Figure  13. — Hydraulic  B  a  c  k- 
Pressure  Valve.  A,  Acetylene  sup- 
ply line;  B,  Vent  pipe;  C,  Water 
filling  plug;  D,  Acetylene  service 
cock;  E,  Plug  to  gaa^e  height  of 
water ;  F,  Gas  openings  under 
water  ;  G,  Return  pipe  for  sealing 
water ;  H,  Tube  to  carry  gas  be- 
low water  line  ;  /,,  Tube  to  carry 
gas  to  escape  pipe  ;  J ' ,  Gas  cham- 
ber ;  K,  Plug  in  upper  gas  cham- 
ber ;  L,  Hish  water  level  ;  M, 
Opening  through  which  water  re- 
turns ;  O,  Bottom  clean  out  cast- 
ing 


ACETYLENE  GENERATORS  83 

water  to  the  space  in  the  top  of  the  cylinder.  From 
there  the  gas  goes  to  the  pipe  leading  to  the  torches. 
The  shorter  pipe  is  closed  by  the  depth  of  water  so 
that  the  gas  does  not  escape  to  the  relief  pipe.  As 
long  as  the  gas  flows  in  the  normal  direction  as  de- 
scribed there  will  be  no  escape  to  the  air.  Should 
the  gas  in  the  torch  line  return  into  the  hydraulic 
valve  its  pressure  will  lower  the  level  of  water  in  the 
cylinder  by  forcing  some  of  the  liquid  up  into  the 
two  pipes.  As  the  level  of  the  water  lowers,  the 
shorter  pipe  will  be  uncovered  first,  and  as  this  is 
the  pipe  leading  to  the  open  air  the  gas  will  be 
allowed  to  escape,  while  the  pipe  leading  back  to  the 
generator  is  still  closed  by  the  water  seal.  As  soon 
as  this  reverse  flow  ceases,  the  water  will  again  resume 
its  level  and  the  action  will  continue.  Because  of 
the  small  amount  of  water  blown  out  of  the  escape 
pipe  each  time  the  valve  is  called  upon  to  perform 
this  duty,  it  is  necessary  to  see  that  the  correct  water 
level  is  always  maintained. 

AVhile  there  are  modifications  of  this  construction, 
the  same  principle  is  used  in  all  types.  The  pressure 
escape  valve  is  often  attached  to  this  hydraulic  valve 
body. 

Construction  Details. — Flexible  tubing  (except  at 
torches),  swring  pipe  joints,  springs,  mechanical  check 
valves,  chains,  pulleys  and  lead  or  fusible  piping 
should  never  be  used  on  acetylene  apparatus  except 
where  the  failure  of  those  parts  will  not  affect  the 
safety  of  the  machine  or  permit,  either  directly  or 
indirectly,  the  escape  of  gas  into  a  room.  Floats 
should  not  be  used  except  where  failure  will  only 
render  the  machine  inoperative. 

It  should  be  said  that  the  National  Board  of  Fire 


84.  WELDING 

Underwriters  have  established  an  inspection  service 
for  acetylene  generators  and  any  apparatus  which 
bears  their  label,  stating  that  that  particular  model 
and  type  has  been  passed,  is  safe  to  use.  This  service 
is  for  the  best  interests  of  all  concerned  and  looks 
toward  the  prevention  of  accidents.  Such  inspection 
is  a  very  important  and  desirable  feature  of  any 
outfit  and  should  be  insisted  upon. 

Location  of  Generators. — Generators  should  pref- 
erably be  placed  outside  of  insured  buildings  and 
in  properly  constructed  generator  houses.  The  oper- 
ating mechanism  should  have  ample  room  to  work 
in  and  there  should  be  room  enough  for  the  attendant 
to  reach  the  various  parts  and  perform  the  required 
duties  without  hindrance  or  the  need  of  artificial 
light.  They  should  also  be  protected  from  tampering 
by  unauthorized  persons. 

Generator  houses  should  not  be  within  five  feet  of 
any  opening  into,  nor  have  any  opening  toward,  any 
adjacent  building,  and  should  be  kept  under  lock  and 
key.  The  size  of  the  house  should  be  no  greater  than 
called  for  by  the  requirements  mentioned  above  and 
it  should  be  well  ventilated. 

The  foundation  for  the  generator  itself  should  be 
of  brick,  stone,  concrete  or  iron,  if  possible.  If  of 
wood,  they  should  be  extra  heavy,  located  in  a  dry- 
place  and  open  to  circulation  of  air.  A  board  plat- 
form is  not  satisfactory,  but  the  foundation  should 
be  of  heavy  planking  or  timber  to  make  a  firm  base 
and  so  that  the  air  can  circulate  around  the  wood. 

The  generator  should  stand  level  and  no  strain 
should  be  placed  on  any  of  the  pipes  or  connections 
or  any  parts  of  the  generator  proper. 


CHAPTER  IV 

WELDING  INSTRUMENTS 

VALVES 

Tank  Valves. — The  acetylene  tank  valve  is  of  the 
needle  type,  fitted  with  suitable  stuffing  box  nuts  and 
ending1  in  an  exposed  square  shank  to  which  the 
special  wrench  may  be  fitted  when  the  valve  is  to  be 
opened  or  closed. 

The  valve  used  on  Linde  oxygen  cylinders  is  also 
a  needle  type,  but  of  slightly  more  complex  construc- 
tion. The  body  of  the  valve,  which  screws  into  the 
top  of  the  cylinder,  has  an  opening  below  through 
which  the  gas  comes  from  the  cylinder,  and  another 
opening  on  the  side  through  which  it  issues  to  the 
torch  line.  A  needle  screws  down  from  above  to 
close  this  lower  opening.  The  needle  which  closes 
the  valve  is  not  connected  directly  to  the  threaded 
member,  but  fits  loosely  into  it.  The  threaded  part 
is  turned,  by  a  small  hand  wheel  attached  to  the  upper 
end.  "When  this  hand  wheel  is  turned  to  the  left,  or 
up,  as  far  as  it  will  go,  opening  the  valve,  a  rubber 
disc  is  compressed  inside  of  the  valve  body  and  this 
disc  serves  to  prevent  leakage  of  the  gas  around  the 
spindle. 

The  oxygen  valve  also  includes  a  safety  nut  having 
a  small  hole  through  it  closed  by  a  fusible  metal 
which  melts  at  250°  Fahrenheit.  Melting  of  this 
plug  allows  the  gas  to  exert  its  pressure  against  a 
thin  copper  diaphragm,  this  diaphragm  bursting 
under  the  gas  pressure  and  allowing  the  oxygen  to 
escape  into  the  air. 

85 


86 


WELDING 


The  hand  wheel  and  upper  end  of  the  valve  mech- 
anism are  protected  during  shipment  by  a  large  steel 
cap  which  covers  them  when  screwed  on  to  the  end 
of  the  cylinder.  This  cap  should  always  be  in  place 
when  tanks  are  received  from  the  makers  or  returned 
to  them. 


>*IGH    PRESSURE 
GAUGE  CON- 


CONNECTION 
TO   OXYGEN   CYLINOCR 


Figure  14. — Regulating  Valve 

Regulating  Valves. — While  the  pressure  in  the 
gas  containers  may  be  anything  from  zero  to  1,800 
pounds,  and  will  vary  as  the  gas  is  withdrawn,  the 
pressure  of  the  gas  admitted  to  the  torch  must  be 
held  steady  and  at  a  definite  point.  This  is  accom- 
plished .by  various  forms  of  automatic  regulating 
valves,  which,  while  they  differ  somewhat  in  details 
of  construction,  all  operate  on  the  same  principle. 

The  regulator  body  (Figure  14)  carries  a  union 
which  attaches  to  the  side  outlet  on  the  oxygen  tank 
valve.  The  gas  passes  through  this  union,  following 


WELDING  INSTRUMENTS  87 

an  opening  which  leads  to  a  large  gauge  which  regis- 
ters the  pressure  on  the  oxygen  remaining  in  the  tank 
and  also  to  a  very  small  opening  in  the  end  of  a  tube. 
The  gas  passes  through  this  opening  and  into  the 
interior  of  the  regulator  body.  Inside  of  the  body 
is  a  metal  or  rubber  diaphragm  placed  so  that  the 
pressure  of  the  incoming  gas  causes  it  to  bulge 
slightly.  Attached  to  the  diaphragm  is  a  sleeve  or 
an  arm  tipped  writh  a  small  piece  of  fibre,  the  fibre 
being  placed  so  that  it  is  directly  opposite  the  small 
hole  through  which  the  gas  entered  the  diaphragm 
chamber.  The  slight  movement  of  the  diaphragm 
draws  the  fibre  tightly  over  the  small  opening  through 
which  the  gas  is  entering,  with  the  result  that  further 
flow  is  prevented. 

Against  the  opposite  side  of  the  diaphragm  is  the 
end  of  a  plunger.  This  plunger  is  pressed  against 
the  diaphragm  by  a  coiled  spring.  The  tension  on 
the  coiled  spring  is  controlled  by  the  operator  through 
a  threaded  spindle  ending  in  a  wing  or  milled  nut  on 
the  outside  of  the  regulator  body.  Screwing  in  on 
the  nut  causes  the  tension  on  the  spring  to  increase, 
with  a  consequent  increase  of  pressure  on  the  side  of 
the  diaphragm  opposite  to  that  on  which  the  gas  acts. 
Inasmuch  as  the  gas  pressure  acted  to  close  the  small 
gas  opening  and  the  spring  pressure  acts  in  the  oppo- 
site direction  from  the  gas,  it  will  be  seen  that  the 
spring  pressure  tends  to  keep  the  valve  open. 

When  the  nut  is  turned  way  out  there  is,  of  course, 
no  pressure  on  the  spring  side  of  the  diaphragm  and 
the  first  gas  coming  through  automatically  closes  the 
opening  through  which  it  entered.  If  now  the  ten- 
sion on  the  spring  be  slightly  increased,  the  valve 
will  again  open  and  admit  gas  until  the  pressure  of 


88  WELDINa 

gas  within  the  regulator  is  just  sufficient  to  overcome 
the  spring  pressure  and  again  close  the  opening. 
There  will  then  be  a  pressure  of  gas  within  the  regu- 
lator that  corresponds  to  the  pressure  placed  on  the 
spring  by  the  operator.  An  opening  leads  from  the 
regulator  interior  to  the  torch  lines  so  that  all  gas 
going  to  the  torches  is  drawn  from  the  diaphragm 
chamber. 

Any  withdrawal  of  gas  will,  of  course,  lower  the 
pressure  of  that  remaining  inside  the  regulator.  The 
spring  tension,  remaining  at  the  point  determined  by 
the  operator,  will  overcome  this  lessened  pressure  of 
the  gas,  and  the  valve  will  again  open  and  admit 
enough  more  gas  to  bring  the  pressure  back  to  the 
starting  point.  This  action  continues  as  long  as  the 
spring  tension  remains  at  this  point  and  as  long  as 
any  gas  is  taken  from  the  regulator.  Increasing  the 
spring  tension  will  require  a  greater  gas  pressure  to 
close  the  valve  and  the  pressure  of  that  in  the  regu- 
lator will  be  correspondingly  higher. 

When  the  regulator  is  not  "being  used,  the  hand 
nut  should  be  unscrewed  until  no  tension  remains  on 
the  spring,  thus  closing  the  valve.  After  the  oxygen 
tank  valve  is  open,  the  regulator  hand  nut  is  slowly 
screwed  in  until  the  spring  tension  is  sufficient  to 
give  the  required  pressure  in  the  torch  lines.  Another 
gauge  is  attached  to  the  regulator  so  that  it  com- 
municates with  the  interior  of  the  diaphragm  cham- 
ber, this  gauge  showing  the  gas  pressure  going  to  the 
torch.  It  is  customary  to  incorporate  a  safety  valve 
in  the  regulator  which  will  blow  off  at  a  dangerous 
pressure. 

In  regulating  valves  and  tank  valves,  as  well  as 
all  other  parts  with  which  the  oxygen  comes  in  con- 


WELDING  INSTRUMENTS 


89 


tact,  it  is  not  permissible  to  use  any  form  of  oil  or 
grease  because  of  danger  of  ignition  and  explosion. 
The  mechanism  of  a  regulator  is  too  delicate  to  be 
handled  in  the  ordinary  shop  and  should  any  trouble 
or  leakage  develop  in  this  part  of  the  equipment  it 
should  be  sent  to  a  company  familiar  with  this  class 
of  work  for  the  necessary  repairs.  Gas  must  never 
be  admitted  to  a  regulator  until  the  hand  nut  is  all 


Figure  15. — High  and  Low  Pressure  Gauges  with  Regulator 


the  way  out,  because  of  danger  to  the  regulator  itself 
and  to  the  operator  as  well.  A  regulator  can  only  be 
properly  adjusted  when  the  tank  valve  and  torch 
valves  are  fully  opened. 

Acetylene  regulators  are  used  in  connection  with 
tanks  of  compressed  gas.  They  are  built  on  exactly 
the  same  lines  as  the  oxygen  regulating  valve  and 
operate  in  a  similar  way.  One  gauge  only,  the  low 
pressure  indicator,  is  used  for  acetylene  regulators, 
although  both  high  and  low  pressure  may  be  used 
if  desired.  (See  Figure  15.) 


90  WELDING 

TORCHES 

Flame  is  always  produced  by  the  combustion  of 
a  gas  with  oxygen  and  in  no  other  way.  When  we 
burn  oil  or  candles  or  anything  else,  the  material  of 
the  fuel  is  first  turned  to  a  gas  by  the  heat  and  is 
then  burned  by  combining  with  the  oxygen  of  the  air. 
If  more  than  a  normal  supply  of  air  is  forced  into 
the  flame,  a  greater  heat  and  more  active  burning 
follows.  If  the  amount  of  air,  and  consequently  oxy- 
gen, is  reduced,  the  flame  becomes  smaller  and  weaker 
and  the  combustion  is  less  rapid.  A  flame  may  be 
easily  extinguished  by  shutting  off  all  of  its  air 
supply. 

The  oxygen  of  the  combustion  only  forms  one-fifth 
of  the  total  volume  of  air;  therefore,  if  we  were  to 
supply  pure  oxygen  in  place  of  air,  and  in  equal 
volume,  the  action  would  be  several  times  as  intense. 
If  the  oxygen  is  mixed  with  the  fuel  gas  in  the  pro- 
portion that  burns  to  the  very  best  advantage,  the 
flame  is  still  further  strengthened  and  still  more  heat 
is  developed  because  of  the  perfect  combustion.  The 
greater  the  amount  of  fuel  gas  that  can  be  burned 
in  a  certain  space  and  within  a  certain  time,  the 
more  heat  will  be  developed  from  that  fuel.' 

The  great  amount  of  heat  contained  in  acetylene 
gas,  greater  than  that  found  in  any  other  gaseous 
fuel,  is  used  by  leadfing  this  gas  to  the  oxy-acetylene 
torch  and  there  combining  it  with  just  the  right 
amount  of  oxygen  to  make  a  flame  of  the  greatest 
power  and  heat  than  can  possibly  be  produced  by  any 
form  of  combustion  of  fuels  of  this  kind.  The  heat 
developed  by  the  flame  is  about  6300°  Fahrenheit  and 
easily  melts  all  the  metals,  as  well  as  other  solids. 


WELDING  INSTRUMENTS  91 

Other  gases  have  been  and  are  now  being  used  in 
the  torch.  None  of  them,  however,  produce  the  heat 
that  acetylene  does,  and  therefore  the  oxy-acetylene 
process  has  proved  the  most  useful  of  all.  Hydrogen 
was  used  for  many  years  before  acetylene  was  intro- 
duced in  this  field.  The  oxy-hydrogen  flame  develops 
a  heat  far  below  that  of  oxy-acetylene,  namely  4500'° 
Fahrenheit.  Coal  gas,  benzine  gas,  blaugas  and 
others  have  also  been  used  in  successful  applications, 
but  for  the  present  we  will  deal  exclusively  with  the 
acetylene  fuel. 

It  was  only  with  great  difficulty  that  the  obstacles 
in  the  way  of  successfully  using  acetylene  were  over- 
come by  the  development  of  practicable  controlling 
devices  and  torches,  as  well  as  generators.  At  pres.- 
ent  the  oxy-acetylene  process  is  the  most  universally 
adaptable,  and  probably  finds  the  most  widely  ex- 
tended field  of  usefulness  of  any  welding  process. 

The  theoretical  proportion  of  the  gases  for  perfect 
combustion  is  two  and  one-half  volumes  of  oxygen  to 
one  of  acetylene.  In  practice  this  proportion  is  one 
and  one-eighth  or  one*  and  one-quarter  volumes  of 
oxygen  to  one  volume  of  acetylene,  so  that  the  cost 
is  considerably  reduced  below  what  it  would  be  if  the 
theoretical  quantity  were  really  necessary,  as  oxygen 
costs  much  more  than  acetylene  in  all  cases. 

While  the  heat  is  so  intense  as  to  fuse  anything 
brought  into  the  path  of  the  flame,  it  is  localized  in 
the  small  "welding  cone"  at  the  torch  tip  so  that 
the  torch  is  not  at  all  difficult  to  handle  without 
special  protection  except  for  the  eyes,  as  already 
noted.  The  art  of  successful  welding  may  be  ac- 
quired by  any  operator  of  average  intelligence  within 
a  reasonable  time  and  with  some  practice.  One 


92  WELDING 

trouble  met  with  in  the  adoption  of  this  process  has 
been  that  the  operation  looks  so  simple  and  so  easy 
of  performance  that  unskilled  and  unprepared  per- 
sons have  been  tempted  to  try  welding,  with  results 
that  often  caused  condemnation  of  the  process,  when 
the  real  fault  lay  entirely  with  the  operator. 

The  form  of  torch  usually  employed  is  from  twelve 
to  twenty-four  inches  long  and  is  composed  of  a 
handle  at  one  end  with  tubes  leading  from  this  handle 
to  the  "welding  head '^ or  torch  proper.  At  or  near 
one  end  of  the  handle  are  adjustable  cocks  or  valves 
for  allowing  the  gases  to  flow  into  the  tojrch  or  to 
prevent  them  from  doing  so.  These  cocks  are  often 
used  for  regulating  the  pressure  and  amount  of  gas 
flowing  to  the  welding  head,  but  are  not  always  con- 
structed for  this  purpose  and  should  not  be  so  used 
when  it  is  possible  to  secure  pressure  adjustment  at 
the  regulators  (Figure  16). 

Figure  16  shows  three  different  sizes  of  torches. 
The  number  5  torch  is  designed  especially  for  jew- 
elers '  work  and  thin  sheet  steel  welding.  It  is  eleven 
inches  in  length  and  weighs  nineteen  ounces.  The 
tips  for  the  number  10  torch  are  interchangeable  with 
the  number  5.  The  number  10  torch  is  adapted  for 
general  use  on  light  and  medium  heavy  work.  It 
has  six  tips  and  its  length  is  sixteen  inches,  with  a 
weight  of  twenty-three  ounces. 

The  number  15  torch  is  designed  for  heavy  work, 
being  twenty-five  inches  in  length,  permitting  the 
operator  to  stand  away  from  the  heat  of  the  metal 
being  worked.  These  heavy  tips  are  in  two  parts,  the 
oxygen  check  being  renewable. 

Figures  17  and  18  show  two- sizes  of  another  weld- 
ing torch.  Still  another  type  is  shown  in  Figure  19 


WELDING   INSTRUMENTS 


93 


g 

(-* 
O5 


H 
tr 


! 


94 


WELDING 


with  four  interchangeable  tips,  the  function  of  each 
being  as  fol]ows: 

No.  1.  For  heavy  castings. 

No.  2.  Light  castings  and  heavy  sheet  metal. 

No.  3.  Light  sheet  metal. 

No.  4.  Very  light  sheet  metal  and  wire. 


4  3  3  t 

Figure  17. — Cox  Welding  Torch  (No.  1) 


Figure  18. — Cox  Welding  Torch  (No.  2) 


Figure  19. — Monarch  Welding  Torch 

At  the  side  of  the  shut  off  cock  away  from  the  torch 
handle  the  gas  tubes  end  in  standard  forms  of  hose 


WELDING  INSTRUMENTS  95 

nozzles,  to  which  the  rubber  hose  from  the  gas  supply 
tanks  or  generators  can  be  attached.  The  tubes  from 
the  handle  to  the  head  may  be  entirely  separate  from 
each  other,  or  one  may  be  contained  within  the  other. 
As  a  general  rule  the  upper  one  of  two  separate  tubes 
carries  the  oxygen,  while  this  gas  is  carried  in  the 
inside  tube  when  they  are  concentric  with  each  other. 

In  the  welding  head  is  the  mixing  chamber  de- 
signed to  produce  an  intimate  mixture  of  the  two 
gases  before  they  issue  from  the  nozzle  to  the  flame. 
The  nozzle,  or  welding  tip,  of  a  suitable  size  and 
design  for  the  work  to  be  handled  and  the  pressure 
of  gases  being  used,  is  attached  to  the  welding  head, 
and  consists  essentially  of  the  passage  at  the  outer 
end  of  which  the  flame  appears. 

The  torch  body  and  tubes  are  usually  made  of 
brass,  although  copper  is  sometimes  used.  The  joints 
must  be  very  strong,  and  are  usually  threaded  and 
soldered  with  silver  solder.  The  nozzle  proper  is 
made  from  copper,  because  it  withstands  the  heat 
of  the  flame  better  than  other  less  suitable  metals. 
The  torch  must  be  built  in  such  a  way  that  it  is  not 
at  all  liable  to  come  apart  under  the  influence  of 
high  temperatures. 

All  torches  are  constructed  in  such  a  way  that  it 
is  impossible  for  the  gases  to  mix  by  any  possible 
chance  before  they  reach  the  head,  and  the  amount 
of  gas  contained  in  the  head  and  tip  after  being 
mixed  is  made  as  small  as  possible.  In  order  to 
prevent  the  return  of  the  flame  through  the  acetylene 
tube  under  the  influence  of  the  high  pressure  oxygen, 
some  form  of  back  flash  preventer  is  usually  incor- 
porated in  the  torch  at  or  near  the  point  at  which 
the  acetylene  enters.  This  preventer  takes  the  form 


96  WELDING 

of  some  porous  and  heat  absorbing  material,  such 
as  aluminum  shavings,  contained  in  a  small  cavity 
through  which  the  gas  passes  on  its  way  to  the  head. 
High  Pressure  Torches. — Torches  are  divided  into 
the  same  classes  as  are  the  generators;  that  is,  high 
pressure,  medium  pressure  and  low  pressure.  As 
mentioned  before,  the  medium  pressure  is  usually 
called  the  high  pressure,  because  there  are  very  few 
true  high  pressure  systems  in  use,  and  comparatively 


Figure  20. — High  Pressure  Torch  Head 

speaking  the  medium  pressure  type  is  one  of  high 
pressure. 

With  a  true  high  pressure  torch  (Figure  20)  the 
gases  are  used  at  very  nearly  equal  heads  so  that  the 
mixing  before  ignition  is  a  simple  matter.  This  type 
admits  the  oxygen  at  the  inner  end  of  a  straight 
passage  leading  to  the  tip  of  the  nozzle.  The  acety- 
lene comes  into  this  same  passage  from  openings  at 
one  side  and  near  the  inner  end.  The  difference  in 
direction  of  the  two  gases  as  they  enter  the  passage 
assists  in  making  a  homogeneous  mixture.  The  con- 
struction of  this  nozzle  is  perfectly  simple  and  is 
easily  understood.  The  true  high  pressure  torch 


WELDING  INSTRUMENTS 


97 


nozzle  is  only  suited  for  use  with  compressed  and 
dissolved  acetylene,  no  other  gas  being  at  a  sufficient 
pressure  to  make  the  action  necessary  in  mixing  the 
gases. 

Medium  Pressure  Torches. — The  medium  pressure 
(usually  called  high  pressure)  torch  (Figure  21) 
uses  acetylene  from  a  medium  pressure  generator 
or  from  tanks  of  compressed  gas,  but  will  not  take 
the  acetylene  from  low  pressure  generators. 


Figure  21. — Medium  Pressure  Torch  Head 

The  construction  of  the  mixing  chamber  and  nozzle 
is  very  similar  to  that  of  the  high  pressure  torch,  the 
gases  entering  in  the  same  way  and  from  the  same 
positions  of  openings.  The  pressure  of  the  acetylene 
is  but  little  lower  than  that  of  the  oxygen,  and  the 
two  gases,  meeting  at  right  angles,  form  a  very  inti- 
mate mixture  at  this  point  of  juncture.  The  mixture 
in  its  proportions  of  gases  depends  entirely  on  the 
sizes  of  the  oxygen  and  acetylene  openings  into  the 
mixing  chamber  and  on  the  pressures  at  which  the 
gases  are  admitted.  There  is  a  very  slight  injector 
action  as  the  fast  moving  stream  of  oxygen  tends  to 
draw  the  acetylene  from  the  side  openings  into  the 


98 


WELDING 


chamber,   but  the  operation   of  the   torch   does  not 
depend  on  this  action  to  any  extent. 

Low  Pressure  Torches. — The  low  pressure  torch 
(Figure  22)  will  use  gas  from  low  pressure  gener- 
ators, from  medium  pressure  machines  or  from  tanks 
in  which  it  has  been  compressed  and  dissolved.  This 
type  depends  for  a  perfect  mixture  of  gas  upon  the 
principle  of  the  injector  just  as  it  is  applied  in  steam 
boiler  practice. 


Figure  22. — Low  Pressure  Torch  with  Separate  Injector  Nozzle 

The  oxygen  enters  the  head  at  considerable  pres- 
sure and  passes  through  its  tube  to  a  small  jet  within 
the  head.  The  opening  of  this  jet  is  directly  opposite 
the  end  of  the  opening  through  the  nozzle  which 
forms  the  mixing  chamber  and  the  path  of  the  gases 
to  the  flame.  A  small  distance  remains  between  the 
opening  from  which  the  oxygen  issues  and  the  inner 
opening  into  the  mixing  passage.  The  stream  of 
oxygen  rushes  across  this  space  and  enters  the  mixing 
chamber,  being  driven  by  its  own  pressure. 

The  acetylene  enters  the  head  in  an  annular  space 
surrounding  the  oxygen  tube.  The  space  between 
oxygen  jet  and  mixing  chamber  opening  is  at  one 


WELDING  INSTRUMENTS  99 

end  of  this  acetylene  space  and  the  stream  of  oxygen 
seizes  the  acetylene  and  under  the  injector  action 
draws  it  into  the  mixing  chamber,  it  being  necessary 
only  to  have  a  sufficient  supply  of  acetylene  flowing 
into  the  head  to  allow  the  oxygen  to  draw  the  re- 
quired proportion  for  a  proper  mixture. 

The  volume  of  gas  drawn  into  the  mixing  chamber 
depends  on  the  size  of  the  injector  openings  and  the 
pressure  of  the  oxygen.  In  practice  the  oxygen 
pressure  is  not  altered  to  produce  different  sized 
flames,  but  a  new  nozzle  is  substituted  which  is 
designed  to  give  the  required  flame.  Each  nozzle 
carries  its  own  injector,  so  that  the  design  is  always 
suited  to  the  conditions.  While  torches  are  made 
having  the  injector  as  a  permanent  part  of  the  torch 
body,  the  replaceable  nozzle  is  more  commonly  used, 
because  it  makes  the  one  torch  suitable  for  a  large 
range  of  work  and  a  large  number  of  different  sized 
flames.  "With  the  replaceable  head  a  definite  pressure 
of  oxygen  is  required  for  the  size  being  used,  this 
pressure  being  the  one  for  which  the  injector  and 
corresponding  mixing  chamber  were  designed  in  pro- 
ducing the  correct  mixture. 

Adjustable  Injectors. — Another  form  of  low  pres- 
sure torch  operates  on  the  injector  principle,  but  the 
injector  itself  is  a  permanent  part  of  the  torch,  the 
nozzle  only  being  changed  for  different  sizes  of  work 
and  flame.  The  injector  is  placed  in  or  near  the 
handle  and  its  opening  is  the  largest  required  by  any 
work  that  can  be  handled  by  this  particular  torch. 
The  opening  through  the  tip  of  the  injector  through 
which  the  oxygen  issues  on  its  way  to  the  mixing 
chamber  may  be  wholly  or  partly  closed  by  a  needle 
valve  which  may  be  screwed  into  the  opening  or 


100  WELDING 

withdrawn  from  it,  according  to  the  operator's  judg- 
ment. The  needle  valve  ends  in  a  milled  nut  outside 
the  torch  handle,  this  being  the  adjustment  provided 
for  the  different  nozzles. 

Torch  Construction. — A  well  designed  torch  is  so 
designed  that  the  weight  distribution  is  best  for  hold- 
ing it  in  the  proper  position  for  welding.  When  a 
torch  is  grasped  by  its  handle  with  the  gas  hose 
attached,  it  should  balance  so  that  it  does  not  feel 
appreciably  heavier  on  one  end  than  on  the  other. 

The  head  and  nozzle  may  be  placed  so  that  the 
flame  issues  in  a  line  at  right  angles  with  the  torch 
body,  or  they  may  be  attached  at  an  angle  convenient 
for  the  work  to  be  done.  The  head  set  at  an  angle 
of  from  120  to  170  degrees  with  the  body  is  usually 
preferred  for  general  work  in  welding,  while  the 
cutting  torch  usually  has  its  head  at  right  angles 
to  the  body. 

Removable  nozzles  have  various  size  openings 
through  them  and  the  different  sizes  are  designated 
by  numbers  from  1  up.  The  same  number  does  not 
always  indicate  the  same  size  opening  in  torches  of 
different  makes,  nor  does  it  indicate  a  nozzle  of  the 
same  capacity. 

The  design  of  the  nozzle,  the  mixing  chamber,  the 
injector,  when  one  is  used,  and  the  size  of  the  gas 
openings  must  be  such  that  all  these  things  are  suited 
to  each  other  if  a  proper  mixture  of  gas  is  to  be 
secured.  Parts  that  are  not  made  to  work  together 
are  unsafe  if  used  because  of  the  danger  of  a  flash 
back  of  the  flame  into  the  mixing  chamber  and  gas 
tubes.  It  is  well  known  that  flame  travels  through 
any  inflammable  gas  at  a  certain  definite  rate  of 
speed,  depending  on  the  degree  of  inflammability  of 


WELDING  INSTRUMJEjS^g?  \J  >>,  \  ]    A  101 


the  gas.  The  easier  and  quicker  the  gas  burns,  the 
faster  will  the  flame  travel  through  it. 

If  the  gas  in  the  nozzle  and  mixing  chamber  stood 
still,  the  flame  would  immediately  travel  back  into 
these  parts  and  produce  an  explosion  of  more  or  less 
violence.  The  speed  with  which  the  gases  issue  from 
the  nozzle  prevent  this  from  happening  because  the 
flame  travels  back  through  the  gas  at  the  same  speed 
at  which  the  gas  issues  from  the  torch  tip.  Should 
the  velocity  of  the  gas  be  greater  than  the  speed  of 
flame  propagation  through  it,  it  will  be  impossible 
to  keep  the  flame  at  the  tip,  the  tendency  being  for 
a  space  of  unburned  gas  to  appear  between  tip  and 
flame.  On  the  other  hand,  should  the  speed  of  the 
flame  exceed  the  velocity  with  which  the  gas  comes 
from  the  torch  there  will  result  a  flash  back  and 
explosion. 

Care  of  Torches.  —  An  oxy-acetylene  torch  is  a  very 
delicate  and  sensitive  device,  much  more  so  than 
appears  on  the  surface.  It  must  be  given  equally 
as  good  care  and  attention  as  any  other  high-priced 
piece  of  machinery  if  it  is  to  be  maintained  in  good 
condition  for  use. 

It  requires  cleaning  of  the  nozzles  at  regular  inter- 
vals if  used  regularly.  This  cleaning  is  accomplished 
with  a  piece  of  copper  or  brass  wire  run  through  the 
opening,  and  never  with  any  metal  such  as  steel  or, 
iron  that  is  harder  than  the  nozzle  itself,  because  of 
the  danger  of  changing  the  size  of  the  openings.  -The 
torch  head  and  nozzle  can  often  be  cleaned  by  allow- 
ing the  oxygen  to  blow  through  at  high  pressure 
without  the  use  of  any  tools. 

In  using  a  torch  a  deposit  of  carbon  will  gradually 
form  inside  of  the  head,  and  this  deposit  will  be  more 


102  *'    c  *    <  WELDING 


rapid  if  the  operator  lights  the  stream  of  acetylene 
before  turning  any  oxygen  into  the  torch.  This 
deposit  may  be  removed  by  running  kerosene  through 
the  nozzle  while  it  is  removed  from  the  torch,  setting 
fire  to  the  kerosene  and  allowing  oxygen  to  flow 
through  while  the  oil  is  burning. 

Should  a  torch  become  clogged  in  the  head  or 
tubes,  it  may  usually  be  cleaned  by  removing  the 
oxygen  hose  from  the  handle  end,  closing  the  acety- 
lene cock  on  the  torch,  placing  the  end  of  the  oxygen 
hose  over  the  opening  in  the  nozzle  and  turning  on 
the  oxygen  under  pressure  to  blow  the  obstruction 
back  through  the  passage  that  it  has  entered.  By 
opening  the  acetylene  cock  and  closing  the  oxygen 
cock  at  the  handle,  the  acetylene  passages  may  then 
be  cleaned  in  the  same  way.  Under  no  conditions' 
should  a  torch  be  taken  apart  any  more  than  to 
remove  the  changeable  nozzle,  except  in  the  hands  of 
those  experienced  in  this  work. 

Nozzle  Sizes. — The  size  of  opening  through  the 
nozzle  is  determined  according  to  the  thickness  and 
kind  of  metal  being  handled.  The  following  sizes 
are  recommended  for  steel : 

Davis-Bournonville.  O  x  w  e  1  d      Low 

Thickness  of  Metal       (Medium  Pressure.)  Pressure 

1/32  Tip  No.  1  Head  No.  2 

1/16  2 

5/64  3 

3/32  3  4 

1/8  4  5 

3/16  5  6 

1/4  6  7 

5/16  7 

3/8  8  8 

1/2  9  10 

5/8  10  12 

3/4  11  15 

Very  heavy  12  15 


WELDING  INSTRUMENTS  103 

Cutting  Torches. — Steel  may  be  cut  with  a  jet  of 
oxygen  at  a  rate  of  speed  greater  than  in  any  other 
practicable  way  under  usual  conditions.  The  action 
consists  of  burning  away  a  thin  section  of  the  metal 
by  allowing  a  stream  of  oxygen  to  flow  onto  it  while 
the  gas  is  at  high  pressure  and  the  metal  at  a  white 
heat. 

The  cutting  torch  (Figure  23)  has  the  same  char- 
acteristics as  the  welding  torch,  but  has  an  additional 
nozzle  or  means  for  temporarily  using  the  welding 


Figure  23. — Cutting  Torch 

opening  for  the  high  pressure  oxygen.  The  oxygen 
issues  from  the  opening  while  cutting  at  a  pressure 
of  from  ten  to  100  pounds  to  the  square  inch. 

The  work  is  first  heated  to  a  white  heat  by  adjust- 
ing the  torch  for  a  welding  flame.  As  soon  as  the 
metal  reaches  this  temperature,  the  high  pressure 
oxygen  is  turned  on  to  the  white-hot  portion  of  the 
steel.  When  the  jet  of  gas  strikes  the  metal  it  cuts 
straight  through,  leaving  a  very  narrow  slot  and 
removing  but  little  metal.  Thicknesses  of  steel  up 
to  ten  inches  can  be  economically  handled  in  this 
way. 

The  oxygen  nozzle  is  usually  arranged  so  that  it 
is  surrounded  by  a  number  of  small  jets  for  the 
heating  flame.  It  will  be  seen  that  this  arrangement 


104  WELDING 

makes  the  heating  flame  always  precede  the  oxygen 
jet,  no  matter  in  which  direction  the  torch  is  moved. 

The  torch  is  held  firmly,  either  by  hand  or  with 
the  help  of  special  mechanism  for  guiding  it  in  the 
desired  path,  and  is  steadily  advanced  in  the  direc- 
tion it  is  desired  to  extend  the  cut,  the  rate  of 
advance  being  from  three  inches  to  two  feet  per 
minute  through  metal  from  nine  inches  down  to  one- 
quarter  of  an  inch  in  thickness. 

The  following  data  on  cutting  is  given  by  the 
Davis-Bournonville  Company : 

•3  5  | 

2  a  *  $$  * 

S       -8         2s  &         s 

°       5         *          °*  ft        ?s 

O  O  ~°  *  -  00 

j     s      I       !!     A    »      * 

II      I       !i     I!    I      !l 

1/4  lOlbs.    41bs.  .40  .086  24  $  .013 

1/2  20  4  .91  .150  15  .029 

3/4  30  4  1.16  .150  15  .036 

1  30  4  1.45  .172  12  .045 
11/2  30  5  2.40  .380  12  .076 

2  40  5  2.96  .380  12  .093 
4  50  5  9.70  .800  7  .299 
6  70  6  21.09  1.50  4  .648 
9  100  6  43.20  2.00  3  1.311 

Acetylene-Air  Torch. — A  form  of  torch  which 
burns  the  acetylene  after  mixing  it  with  atmospheric 
air  at  normal  pressure  rather  than  with  the  oxygen 
under  higher  pressures  has  been  found  useful  in 
certain  pre-heating,  brazing  and  similar  operations. 
This  torch  (Figure  24)  is  attached  by  a  rubber  gas 
hose  to  any  compressed  acetylene  tank  and  is  regu- 
lated as  to  flame  size  and  temperature  by  opening  or 
closing  the  tank  valve  more  or  less. 


WELDING  INSTRUMENTS  105 

After  attaching  the  torch  to  the  tank,  the  gas  is 
turned  on  very  slowly  and  is  lighted  at  the  torch  tip. 
The  adjustment  should  cause  the  presence  of  a  green- 
ish-white cone  of  flame  surrounded  by  a  larger  body 
of  burning  gas,  the  cone  starting  at  the  mouth  of 
the  torch. 

By  opening  the  tank  valve  more,  a  longer  and 
hotter  flame  is  produced,  the  length  being  regulated 


Figure  24. — Acetylene-Air  Torch 

. 

by  the  tank  valve  also.  This  torch  will  give  sufficient 
heat  to  melt  steel,  although  not  under  conditions 
suited  to  welding.  Because  of  the  excess  of  acetylene 
always  present  there  is  no  danger  of  oxidizing  the 
metal  being  heated. 

The  only  care  required  by  this  torch  is  to  keep  the 
small  air  passages  at  the  nozzle  clean  and  free  from 
carbon  deposits.  The  flame  should  be  extinguished 
when  not  in  use  rather  than  turned  low,  because  this 
low  flame  rapidly  deposits  large  quantities  of  soot 
in  the  burner. 


CHAPTER  V 

OXY-ACETYLENE  WELDING  PEACTICE 
PREPARATION  OF  WORK 

Preheating. — The  practice  of  heating  the  metal 
around  the  weld  before  applying  the  torch  flame  is 
a  desirable  one  for  two  reasons.  First,  it  makes  the 
whole  process  more  economical;  second,  it  avoids  the 
danger  of  breakage  through  expansion  and  contrac- 
tion of  the  work  as  it  is  heated  and  as  it  cools. 

When  it  is  desired  to  join  two  surfaces  by  welding 
them,  it  is,  of  course,  necessary  to  raise  the  metal 
from  the  temperature  of  the  surrounding  air  to  its 
melting  point,  involving  an  increase  in  temperature 
of  from  one  thousand  to  nearly  three  thousand  de-' 
grees.  To  obtain  this  entire  increase  of  temperature 
with  the  torch  flame  is  very  wasteful  of  fuel  and  of 
the  operator's  time.  The  total  amount  of  heat  nec- 
essary to  put  into  metal  is  increased  by  the  con- 
ductivity of  that  metal  because  the  heat  applied  at 
the  weld  is  carried  to  other  parts  of  the  piece  being 
handled  until  the  whole  mass  is  considerably  raised 
in  temperature.  To  secure  this  widely  distributed 
increase  the  various  methods  of  preheating  are 
adopted. 

As  to  the  second  reason  for  preliminary  heating. 
It  is  understood  that  the  metal  added  to  the  joint  is 
molten  at  the  time  it  flows  into  place.  All  the  metals 
used  in  welding  contract  as  they  cool  and  occupy 
a  much  smaller  space  than  when  molten.  If  addi- 
tional metal  is  run  between  two  adjoining  surfaces 
which  are  parts  of  a  surrounding  body  of  cool  metal, 

106 


OXY-ACETYLENE  WELDING  PRACTICE  107 

this  added  metal  will  cool  while  the  surfaces  them- 
selves are  held  stationary  in  the  position  they  Grig-* 
in  ally  occupied.  The  inevitable  result  is  that  the 
metal  added  will  crack  under  the  strain,  or,  if  the 
weld  is  exceptionally  strong,  the  main  body  of  the 
work  will  be  broken  by  the  force  of  contraction.  To 
overcome  these  difficulties  is  the  second  and  most 
important  reason  for  preheating  and  also  for  slow 
cooling  following  the  completion  of  the  weld. 

There  are  many  ways  of  securing  this  preheating. 
The  work  may  be  brought  to  a  red  heat  in  the  forge 
if  it  is  cast  iron  or  steel ;  it  may  be  heated  in  special 
ovens  built  for  the  purpose;  it  may  be  placed  in  a 
bed  of  charcoal  while . suitably  supported;  it  may  be 
heated  by  gas  or  gasoline  preheating  torches,  and 
with  very  small  Work  the  outer  flame  of  the  welding 
torch  automatically  provides  means  to  this  end. 

The  temperature  of  the  parts  heated  should  be 
gradually  raised  in  all  cases,  giving  the  entire  mass 
of  metal  a  chance  to  expand  equally  arid  to  adjust 
itself  to  the  strains  imposed  by  the  preheating.  After 
the  region  around  the  weld  has  been  brought  to  a 
proper  temperature  the  opening  to  be  filled  is  ex- 
posed so  that  the  torch  flame  can  reach  it,  while  the 
remaining  surfaces  are  still  protected  from  cold  air 
currents  and  from  cooling  through  natural  radiation. 

One  of  the  commonest  methods  and  one  of  the  best 
for  handling  work  of  rather  large  size  is  to  place  the 
piece  to  be  welded  on  a  bed  of  fire  brick  and  build 
a  loose  wall  around  it  with  other  fire  brick  placed  in 
rows,  one  on  top  of  the  other,  with  air  spaces  left 
between  adjacent  bricks  in  each  row.  The  space 
between  the  brick  retaining  wall  and  the  work  is 
filled  with  charcoal,  which  is  lighted .  from  below. 


108 

The  top  opening  of  the  temporary  oven  is  then  cov- 
ered with  asbestos  and  the  fire  kept  up  until  the 
work  has  been  uniformly  raised  in  temperature  to 
the  desired  point. 

When  much  work  of  the  same  general  character 
and  size  is  to  be  handled,  a  permanent  oven  may  be 
constructed  of  fire  brick,  leaving  a  large  opening 
through  the  top  and  also  through  one  side.  Charcoal 
may  be  used  in  this  form  of  oven  as  with  the  tem- 
porary arrangement,  or  the  heat  may  be  secured 
from  any  form  of  burner  or  torch  giving  a  large 
volume  of  flame.  In  any  method  employing  flame  to 
do  the  heating,  the  work  itself  must  be  protected 
from  the  direct  blast  of  the  fire.  Baffles  of  brick  or 
metal  should  be  placed  between  the  mouth  of  the 
torch  and  the  nearest  surface  of  the  work  so  that 
the  flame  will  be  deflected  to  either  side  and  around 
the  piece  being  heated. 

The  heat  should  be  applied  to  bring  the  point  of 
welding  to  the  highest  temperature  desired  and,  ex- 
cept in  the  smallest  work,  the  heat  should  gradually 
shade  off  from  this  point  to  the  other  parts  of  the 
piece.  In  the  case  of  cast  iron  and  steel  the  tem- 
perature at  the  point  to  be  welded  should  be  great 
enough  to  produce  a  dull  red  heat.  This  will  make 
the  whole  operation  much  easier,  because  there  will 
be  no  surrounding  cool  metal  to  reduce  the  tempera- 
ture of  the  molten  material  from  the  welding  rod 
below  the  point  at  which  it  will  join  the  work.  From 
this  red  heat  the  mass  of  metal  should  grow  cooler 
as  the  distance  from  the  weld  becomes  greater,  so 
that  no  great  strain  is  placed  upon  any  one  part. 
With  work  of  a  very  irregular  shape  it  is  always 
best  to  heat  the  entire  piece  so  that  the  strains  will 


OXY-ACETYLENE  WELDING  PRACTICE  109 

be  so  evenly  distributed  that  they  can  cause  no  dis- 
tortion or  breakage  under  any  conditions. 

The  melting  point  of  the  work  which  is  being  pre- 
heated should  be  kept  in  mind  and  care  exercised  not 
to  approach  it  too  closely.  Special  care  is  necessary 
with  aluminum  in  this  respect,  because  of  its  low 
melting  temperature  and  the  sudden  weakening  and 
flowing  without  warning.  Workmen  have  carelessly 
overheated  aluminum  castings  and,  upon  uncovering 
the  piece  to  make  the  weld,  have  been  astonished  to 
find  that  it  had  disappeared.  Six  hundred  degrees 
is  about  the  safe  limit  for  this  metal.  It  is  possible 
to  gauge  the  exact  temperature  of  the  work  with  a 
pyrometer,  but  when  this  instrument  cannot  be  pro- 
cured, it  might  be  well  to  secure  a  number  of  "tem- 
perature cones"  from  a  chemical  or  laboratory  sup- 
ply house.  These  cones  are  made  from  material  that 
will  soften  at  a  certain  heat  and  in  form  they  are 
long  and  pointed.  Placed  in  position  on  the  part 
being  heated,  the  point  may  be  watched,  and  when 
it  bends  over  it  is  sure  that  the  metal  itself  has 
reached  a  temperature  considerably  in  excess  of  the 
temperature  at  which  that  particular  cone  was  de- 
signed to  soften. 

The  object  in  preheating  the  metal  around  the 
weld  is  to  cause  it  to  expand  sufficiently  to  open  the 
crack  a  distance  equal  to  the  contraction  when  cool- 
ing from  the  melting  point.  In  the  case  of  a  crack 
running  from  the  edge  of  a  piece  into  the  body  or 
of  a  crack  wholly  within  the  body,  it  is  usually  satis- 
factory to  heat  the  metal  at  each  end  of  the  opening. 
This  will  cause  the  whole  length  of  the  crack  to  open 
sufficiently  to  receive  the  molten  material  from  the 
rod. 


110 


WELDING 


The  judgment  of  the  operator  will  be  called  upon 
to  decide  just  where  a  piece  of  metal  should  be  heated 
to  open  the  weld  properly.  It  is  often  possible  to 
apply  the  preheating  flame  to  a  point  some  distance 
from  the  point  of  work  if  the  parts  are  so  connected 


^gS^s^^S 


I^S^i 


gi^^;sgs$^^!^^^^^^ 


•ggsaa^y^sscassissss 


s^s^Sd 


Figure  25. — Preheating  at  A  While  Welding  at  B.     C  also  May  Be 
Heated 

that  the  expansion  of  the  heated  part  will  serve  to 
draw  the  edges  of  the  weld  apart.  Whatever  part 
of  the  work  is  heated  to  cause  expansion  and  separa- 
tion, this  part  must  remain  hot  during  the  entire 
time  of  welding  and  must  then  cool  slowly  at  the 
same  time  as  the  metal  in  the  weld  cools. 

An  example  of  heating  points  away  from  the  crack 
might  be  found  in  welding  a  lattice  work  with  one 


OXY-ACETYLENE  WELDING  PRACTICE        111 

of  the  bars  cracked  through  (Figure  25).  If  the 
strips  parallel  and  near  to  the  broken  bar  are  heated 
gradually,  the  work  will  be  so  expanded  that  the 
edges  of  the  break  are  drawn  apart  and  the  weld 
can  be  successfully  made.  In  this  case,  the  parallel 
bars  next  to  the  broken  one  would  be  heated  highest, 
the  next  row  not  quite  so  hot  and  so  on  for  some 
distance  away.  If  only  the  one  row  were  heated,  the 


Figure  26. — Cutting  Through  the  Rim  of  a  Wheel  (Cut  Shown  at  A) 

strains  set  up  in  the  next  ones  would  be  sufficient 
to  cause  a  new  break  to  appear. 

If  welding  is  to  be  done  near  the  central  portion 
of  a  large  piece,  the  strains  will  be  brought  to  bear 
on  the  parts  farthest  away  from  the  center.  Should 
a  fly  wheel  spoke  be  broken  and  made  ready  to  weld, 
the  greatest  strain  will  come  on  the  rim  of  the  wheel. 
In  cases  like  this  it  is  often  desirable  to  cut  through 
at  the  point  of  greatest  strain  with  a  saw  or  cutting 
torch,  allowing  free  movement  while  the  weld  is 
made  at  the  original  break  (Figure  26).  After  the 


112  WELDING 

inside  weld  is  completed,  the  cut  may  be  welded 
without  danger,  for  the  reason  that  it  will  always 
be  at  some  point  at  which  severe  strains  cannot  be 
set  up  by  the  contraction  of  the  cooling  metal. 

In  materials  that  will  spring  to  some  extent  with- 
out breakage,  that  is,  in  parts  that  are  not  brittle,  it 
may  be  possible  to  force  the  work  out  of  shape  with 
jacks  or  wedges  (Figure  27)  in  the  same  way  that 
it  would  be  distorted  by  heating  and  expanding  some 
portion  of  it  as  described.  A  careful  examination 
will  show  whether  this  method  can  be  followed  in 
such  a  way  as  to  force  the  edges  of  the  break  to 


Figure  27. — Using  a  Wedge  While  Welding 

separate.  If  the  plan  seems  feasible,  the  wedges 
may  be  put  in  place  and  allowed  to  remain  while  the 
weld  is  completed.  As  soon  as  the  work  is  finished 
the  wedges  should  be  removed  so  that  the  natural 
contraction  can  take  place  without  damage. 

It  should  always  be  remembered  that  it  is  not  so 
much  the  expansion  of  the  work  when  heated  as  it 
is  the  contraction  caused  by  cooling  that  will  do  the 
damage.  A  weld  may  be  made  that,  to  all  appear- 
ances, is  perfect  and  it  may  be  perfect  when  com- 
pleted; but  if  provision  has  not  been  made  to  allow 
for  the  contraction  that  is  certain  to  follow,  there 
will  be  a  breakage  at  some  point.  It  is  not  possible 
to  weld  the  simplest  shapes,  other  than  straight  bars, 
without  considering  this  difficulty  and  making  pro- 
vision to  take  care  of  it. 


OXY-ACETYLENE   WELDING  PRACTICE  113 

The  exact  method  to  employ  in  preheating  will 
always  call  for  good  judgment  on  the  part  of  the 
workman,  and  he  should  remember  that  the  success 
or  failure  of  his  work  will  depend  fully  as  much  on 
proper  preparation  as  on  correct  handling  of  the 
wreld  itself.  It  should  be  remembered  that  the  outer 
flame  of  the  oxy-acetylene  torch  may  be  depended 
on  for  a  certain  amount  of  preheating,  as  this  flame 
gives  a  very  large  volume  of  heat,  but  a  heat  that 
is  not  so  intense  nor  so  localized  as  the  welding  flame 
itself.  The  heat  of  this  part  of  the  flame  should  be 
fully  utilized  during  the  operation  of  melting  the 
metal  and  it  should  be  so  directed,  when  possible, 
that  it  will  bring  the  parts  next  to  be  joined  to  as 
high  a  temperature  as  possible. 

When  the  work  has  been  brought  to  the  desired 
temperature,  all  parts  except  the  break  and  the  sur- 
face immediately  surrounding  it  on  both  sides  should 
be  covered  with  heavy  sheet  asbestos.  This  protect- 
ing cover  should  remain  in  place  throughout  the 
operation  and  should  only  be  moved  a  distance  suffi- 
cient to  allow  the  torch  flame  to  travel  in  the  path 
of  the  weld.  The  use  of  asbestos  in  this  way  serves 
a  twofold  purpose.  It  retains  the  heat  in  the  work 
and  prevents  the  breakage  that  would  follow  if  a 
draught  of  air  were  to  strike  the  heated  metal, 
and  it  also  prevents  such  a  radiation  of  heat  through 
the  surrounding  air  as  would  make  it  almost  impos- 
sible for  the  operator  to  perform  his  work,  especially 
in  the  case  of  large  and  heavy  castings  when  the 
amount  of  heat  utilized  is  large. 

Cleaning  and,  Champ  fering. — A  perfect  weld  can 
never  be  made  unless  the  surfaces  to  be  joined  have 
been  properly  prepared  to  receive  the  new  metal. 


114  WELDING 

All  spoiled,  burned,  corroded  and  rough  particles 
must  positively  be  removed  with  .chisel  and  hammer 
and  with  a  free  application  of  emery  cloth  and  wire 
brush.  The  metal  exposed  to  the  welding  flame 
should  be  perfectly  clean  and  bright  all  over,  or 
else  the  additional  material  will  not  unite,  but  will 
only  stick  at  best. 

Following  the  cleaning  it  is  always  necessary  to 
bevel,  or  champfer,  the  edges  except  in  the  thinnest 


Figure  28. — Tapering  the  Opening  Formed  by  a  Break 

sheet  metal.  To  make  a  weld  that  will  hold,  the 
metal  must  be  made  into  one  piece,  without  holes  or 
unfilled  portions  at  any  point,  and  must  be  solid 
from  inside  to  outside.  This  can  only  be  accom- 
plished by  starting  the  addition  of  metal  at  one 
point  and  gradually  building  it  up  until  the  outside, 
or  top,  is  reached.  With  comparatively  thin  plates 
the  molten  metal  may  be  started  from  the  side  far- 
thest from  the  operator  and  brought  through,  but 
with  thicker  sections  the  addition  is  started  in  the 
middle  and  brought  flush  with  one  side  and  then 
with  the  other. 

It  will  readily  be  seen  that  the  molten  material 


OXY-ACETYLENE  WELDING  PRACTICE        115 

cannot  be  depended  upon  to  flow  between  the  tightly 
closed  surfaces  of  a  crack  in  a  way  that  can  be  at  all 
sure  to  make  a  true  weld.  It  will  be  necessary  for 
the  operator  to  reach  to  the  farthest  side  with  the 
flame  and  welding  rod,  and  to  start  the  new  surfaces 
there.  To  allow  this,  the  edges  that  are  to  be  joined 
are  beveled  from  one  side  to  the  other  (Figure  28), 
so  that  when  placed  together  in  approximately  the 
position  they  are  to  occupy  they  will  leave  a  grooved 
channel  between  them  with  its  sides  at  an  angle  with 


\ 


Figure  29. — Beveling  for  Thin  Work 


Figure  30. — Beveling  for  Thick  Work 

each  other  sufficient  in  size  to  allow  access  to  every 
point  of  each  surface. 

With  work  less  than  one-fourth  inch  thick,  this 
angle  should  be  forty-five  degrees  on  each  piece 
(Figure  29),  so  that  when  they  are  placed  together 
the  extreme  edges  will  meet  at  the  bottom  of  a 
groove  whose  sides  are  square,  or  at  right  angles, 
to  each  other.  This  beveling  should  be  done  so  that 
only  a  thin  edge  is  left  where  the  two  parts  come 
together,  just  enough  points  in  contact  to  make  the 
alignment  easy  to  hold.  With  work  of  a  thickness 
greater  than  a  quarter  of  an  inch,  the  angle  of  bevel 
on  each  piece  may  be  sixty  degrees  (Figure  30),  so 
that  when  placed  together  the  angle  included  be- 


116 


WELDING 


tween  the  sloping  sides  will  also  be  sixty  degrees. 
If  the  plate  is  less  than  one-eighth  of  an  inch  thick 
the  beveling  is  not  necessary,  as  the  edges  may  be 
melted  all  the  way  through  without  danger  of  leaving 
blowholes  at  any  point. 

This  beveling  may  be  done  in  any  convenient  way. 
A  chisel  is  usually  most  satisfactory  and  also  quick- 
est. Small  sections  may  be  handled  by  filing,  while 
metal  that  is  too  hard  to  cut  in  either  of  these  wavs 


Figure  31. — Beveling  Both  Sides  of  a  Thick  Piece 


Figure  32. — Beveling  the  End  of  a  Pipe 

may  be  shaped  on  the  emery  wheel.  It  is  not  nec- 
essary that  the  edges  be  perfectly  finished  and  abso- 
lutely smooth,  but  they  should  be  of  regular  outline 
and  should  always  taper  off  to  a  thin  edge  so  that 
when  the  flame  is  first  applied  it  can  be  seen  issuing 
from  the  far  side  of  the  crack.  If  the  work  is  quite 
thick  and  is  of  a  shape  that  will  allow  it  to  be  turned 
over,  the  bevel  may  be  brought  from  both  sides 
(Figure  31),  so  that  there  will  be  two  grooves,  one 
on  each  surface  of  the  work.  After  completing  the 
weld  on  one  side,  the  piece  is  reversed  and  finished 
on  the  other  side.  Figure  32  shows  the  proper  bevel- 


OXY-ACETYLENE  WELDING  PRACTICE  117 

ing  for  welding  pipe.     Figure  33  shows  how  sheet 
metal  may  be  flanged  for  welding. 

Welding  should  not  be  attempted  with  the  edges 
separated  in  place  of  beveled,  because  it  will  be 
found  impossible  to  build  up  a  solid  web  of  new 
metal  from  one  side  clear  through  to  the  other  by 
this  method.  The  flame  cannot  reach  the  surfaces 
to  make  them  molten  while  receiving  new  material 
from  the  rod,  and  if  the  flame  does  not  reach  them 
it  will  only  serve  to  cause  a  few  drops  of  the  metal 
to  join  and  will  surely  cause  a  weak  and  defective 
weld. 

, nn _, 

i  JV__ 


Figure  33. — Flanging  Sheet  Metal  for  Welding 

Supporting  Work. — During  the  operation  of  weld- 
ing it  is  necessary  that  the  work  be  well  supported 
in  the  position  it  should  occupy.  This  may  be  done 
with  fire  brick  placed  under  the  pieces  in  the  correct 
position,  or,  better  still,  with  some  form  of  clamp. 
The  edges  of  the  crack  should  touch  each  other  at 
the  point  where  welding  is  to  start  and  from  there 
should  gradually  separate  at  the  rate  of  about  one- 
fourth  inch  to  the  foot.  This  is  done  so  that  the 
cooling  of  the  molten  metal  as  it  is  added  will  draw 
the  edges  together  by  its  contraction. 

Care  must  be  used  to  see  that  the  work  is  sup- 
ported so  that  it  will  maintain  the  same  relative 
position  between  the  parts  as  must  be  present  when 
the  work  is  finished.  In  this  connection  it  must  be 


118 


WELDING 


remembered  that  the  expansion  of  the  metal  when 
heated  may  be  great  enough  to  cause  serious  dis- 
tortion and  to  provide  against  this  is  one  of  the 
difficulties  to  be  overcome. 

Perfect  alignment  should  be  secured  between  the 
separate  parts  that  are  to  be  joined  and  the  two 
edges  must  be  held  up  so  that  they  will  be  in  the 
same  plane  while  welding  is  carried  out.  If,  by  any 
chance,  one  drops  below  the  other  while  molten  metal 


Figure  34. — Rotary  Movement  of  Torch  in  Welding 

is  being  added,  the  whole  job  may  have  to  be  undone 
and  done  over  again.  One  precaution  that  is  nec- 
essary is  that  of  making  sure  that  the  clamping  or 
supporting  does  not  in  itself  pull  the  work  out  of 
shape  while  melted. 

TORCH    PRACTICE 

The  weld  is  made  by  bringing  the  tip  of  the  weld- 
ing flame  to  the  edges  of  the  metals  to  be.  joined. 
The  torch  should  be  held  in  the  right  hand  and 
moved  slowly  along  the  crack  with  a  rotating  motion, 
traveling  in  small  circles  (Figure  34),  so  that  the 


OXY-ACETYLENE  WELDING  PRACTICE        119 

welding  flame  touches  first  on  one  side  of  the  crack 
and  then  on  the  other.  On  large  work  the  motion 
may  be  simply  back  and  forth  across  the  crack, 
advancing  regularly  as  the  metal  unites.  It  is 
usually  best  to  weld  toward  the  operator  rather  than 
from  him,  although  this  rule  is  governed  by  circum- 
stances. The  head  of  the  torch  should  be  inclined 
at  an  angle  of  about  %60  degrees  to  the  surface  of  the 
work.  The  torch  handle  should  extend  in  the  same 
line  with  the  break  (Figure  35)  and  not  across  it, 
except  when  welding  very  light  plates. 


Figure  35. — Torch  Held  in  Line  with  the  Break 

If  the  metal  is  1/16  inch  or  less  in  thickness  it  is 
only  necessary  to  circle  along  the  crack,  the  metal 
itself  furnishing  enough  material  to  complete  the 
weld  without  additions.  Heat  both  sides  evenly  until 
they  flow  together. 

Material  thicker  than  the  above  requires  the  addi- 
tion of  more  metal  of  the  same  or  different  kind  from 
the  welding  rod,  this  rod  being  held  by  the  left  hand. 
The  proper  size  rod  for  cast  iron  is  one  having  a 
diameter  equal  to  the  thickness  of  metal  being  welded 
up  to  a  one-half  inch  rod,  which  is  the  largest  used. 
For  steel  the  rod  should  be  one-half  the  thickness 
of  the  metal  being  joined  up  to  one-fourth  inch  rod. 


120 


WELDING 


As  a  general  rule,  better  results  will  be  obtained 
by  the  use  of  smaller  rods,  the  very  small  sizes  being 
twisted  together  to  furnish  enough  material  while 
retaining  the  free  melting  qualities. 

The  tip  of  the  rod  must  at  all  times  be  held  in 
contact  with  the  pieces  being  welded  and  the  flame 


Figure  36. — The  Welding  Rod  Should  Be  Held  in  the  Molten  Metal 

must  be  so  directed  that  the  two  sides  of  the  crack 
and  the  end  of  the  rod  are  melted  at  the  same  time 
(Figure  36).  Before  anything  is  added  from  the 
rod,  the  sides  of  the  crack  are  melted  down  suffi- 
ciently to  fill  the  bottom  of  the  groove  and  join  the 


Figure  37. — Welding  Pieces  of  Unequal  Thickness 

two  sides.  Afterward,  as  metal  comes  from  the  rod 
in  filling  the  crack,  the  flame  is  circled  along  the 
joint  being  made,  the  rod  always  following  the 
flame. 

Figure    37    illustrates    the    welding    of   pieces   of 
unequal  thickness. 


OXY-ACETYLENE  WELDING   PRACTICE  121 

Figure  38  illustrates  welding  at  an  angle. 

The  molten  metal  may  be  directed  as  to  where  it 
should  go  by  the  tip  of  the  welding  flame,  which  has 
considerable  force,  but  care  must  be  taken  not  to 
blow  melted  metal  on  to  cooler  surfaces  which  it 
cannot  join.  If,  while  welding,  a  spot  appears  which 
does  not  unite  with  the  weld,  it  may  be  handled  by 
heating  all  around  it  to  a  white  heat  and  then  imme- 
diately welding  the  bad  place. 


J 


Figure  38. — Welding  at  an  Angle 


Never  stop  in  the  middle  of  a  weld,  as  it  is  ex- 
tremely difficult  to  continue  smoothly  when  resuming 
work. 

The  Flame. — The  welding  flame  must  have  exactly 
the  right  proportions  of  each  gas.  If  there  is  too 
much  oxygen,  the  metal  will  be  burned  or  oxidized; 
the  presence  of  too  much  acetylene  carbonizes  the 
metal;  that  is  to  say,  it  adds  carbon  and  makes  the 
work  harder.  Just  the  right  mixture  will  neither 
burn  nor  carbonize  and  is  said  to  be  a  "neutral" 
flame.  The  neutral  flame,  if  of  the  correct  size  for 
the  work,  reduces  the  metal  to  a  melted  condition, 
not  too  fluid,  and  for  a  width  about  the  same  as  the 
thickness  of  the  metal  being  welded. 

"When  ready  to  light  the  torch,  after  attaching  the 


122  WELDING 

right  tip  or  head  as  directed  in  accordance  with  the 
thickness  of  metal  to  be  handled,  it  will  be  necessary 
to  regulate  the  pressure  of  gases  to  secure  the  neutral 
flame. 

The  oxygen  will  have  a  pressure  of  from  2  to  20 
pounds,  according  to  the  nozzle  used.  The  acetylene 
will  have  much  less.  Even  with  the  compressed  gas, 
the  pressure  should  never  exceed  10  pounds  for  the 
largest  work,  and  it  will  usually  be  from  4  to  6. 
In  low  pressure  systems,  the  acetylene  will  be  re- 
ceived at  generator  pressure.  It  should  first  be  seen 
that  the  hand-screws  on  the  regulators  are  turned 
way  out  so  that  the  springs  are  free  from  any  ten- 
sion. It  will  do  no  harm  if  these  screws  are  turned 
back  until  they  come  out  of  the  threads.  This  must 
be  done  with  both  oxygen  and  acetylene  regulators. 

Next,  open  the  valve  from  the  generator,  or  on 
the  acetylene  tank,  and  carefully  note  whether  there 
is  any  odor  of  escaping  gas.  Any  leakage  of  this 
gas  must  be  stopped  before  going  on  with  the  work. 

The  hand  wheel  controlling  the  oxygen  cylinder 
valve  should  now  be  turned  very  slowly  to  the  left 
as  far  as  it  will  go,  which  opens  the  valve,  and  it 
should  be  borne  in  mind  the  pressure  that  is  being 
released.  Turn  in  the  hand  screw  on  the  oxygen 
regulator  until  the  small  pressure  gauge  shows  a 
reading  according  to  the  requirements  of  the  noz- 
zle being  used.  This  oxygen  regulator  adjustment 
should  be  made  with  the  cock  on  the  torch  open, 
and  after  the  regulator  is  thus  adjusted  the  torch 
cock  may  be  closed. 

Open  the  acetylene  cock  on  the  torch  and  screw 
in  on  the  acetylene  regulator  hand-screw  until  gas 
commences  to  come  through  the  torch.  Light  this 


OXY-ACETYLENE  WELDING  PRACTICE  123 

flow  of  acetylene  and  adjust  the  regulator  screw  to 
the  pressure  desired,  or,  if  there  is  no  gauge,  so  that 
there  is  a  good  full  flame.  With  the  pressure  of 
acetylene  controlled  by  the  type  of  generator  it  will 
only  be  necessary  to  open  the  torch  cock. 

With  the  acetylene  burning,  slowly  open  the  oxy- 
gen cock  on  the  torch  and  allow  this  gas  to  join  the 
flame.  The  flame  will  turn  intensely  bright  and  then 
blue  white.  There  will  be  an  outer  flame  from  four 
to  eight  inches  long  and  from  one  to  three  inches 
thick.  Inside  of  this  flame  will  be  two  more  rather 
distinctly  defined  flames.  The  inner  one  at  the  torch 
tip  is  very  small,  and  the  intermediate  one  is  long 
and  pointed.  The  oxygen  should  be  turned  on  until 
the  two  inner  flames  unite  into  one  blue-white  cone 
from  one-fourth  to  one-half  inch  long  and  one-eighth 
to  one-fourth  inch  in  diameter.  If  this  single,  clearly 
defined  cone  does  not  appear  when  the  oxygen  torch 
cock  has  been  fully  opened,  turn  off  some  of  the 
acetylene  until  it  does  appear. 

If  too  much  oxygen  is  added  to  the  flame,  there 
will  still  be  the  central  blue-white  cone,  but  it  will 
be  smaller  and  more  or  less  ragged  around  the  edges 
(Figure  39).  When  there  is  just  enough  oxygen  to 
make  the  single  cone,  and  when,  by  turning  on  more 
acetylene  or  by  turning  off  oxygen,  two  cones  are 
caused  to  appear,  the  flame  is  neutral  (Figure  40), 
and  the  small  blue-white  cone  is  called  the  welding 
flame. 

While  welding,  test  the  correctness  of  the  flame 
adjustment  occasionally  by  turning  on  more  acety- 
lene or  by  turning  off  some  oxygen  until  two  flames 
or  cones  appear.  Then  regulate  as  before  to  secure 
the  single  distinct  cone.  Too  much  oxygen  is  not 


124  WELDING 


usually  so  harmful  as  too  much  acetylene,  except 
with  aluminum.  (See  Figure  41.)  An  excessive 
amount  of  sparks  coming  from  the  weld  denotes  that 


Figure  39. — Oxidizing  Flame — Too  Much  Oxygen 


Figure  40. — Neutral  Flame 


Figure  41. — Reducing  Flame — Showing  an  Excess  of  Acetylene 


OXY-ACETYLENE  WELDING  PRACTICE  125 

there  is  too  much  oxygen  in  the  flame.  Should  the 
opening  in  the  tip  become  partly  clogged,  it  will  be 
difficult  to  secure  a  neutral  flame  and  the  tip  should 
be  cleaned  with  a  brass  or  copper  wire — never  with 
iron  or  steel  tools  or  wire  of  any  kind.  While  the 
torch  is  doing  its  work,  the  tip  may  become  exces- 
sively hot  due  to  the  heat  radiated  from  the  molten 
metal.  The  tip  may  be  cooled  by  turning  off  the 
acetylene  and  dipping  in  water  with  a  slight  flow 
of  oxygen  through  the  nozzle  to  prevent  water  find- 
ing its  way  into  the  mixing  chamber. 

The  regulators  for  cutting  are  similar  to  those  for 
welding,  except  that  higher  pressures  may  be  han- 
dled, and  they  are  fitted  with  gauges  reading  up  to 
200  or  250  pounds  pressure. 

In  welding  metals  which  conduct  the  heat  very 
rapidly  it  is  necessary  to  use  a  much  larger  nozzle 
and  flame  than  for  metals  which  have  not  this  prop- 
erty. This  peculiarity  is  found  to  the  greatest  extent 
in  copper,  aluminum  and  brass. 

Should  a  hole  be  blown  through  the  work,  it  may 
be  closed  by  withdrawing  the  flame  for  a  few  sec- 
onds and  then  commencing  to  build  additional  metal 
around  the  edges,  working  all  the  way  around  and 
finally  closing  the  small  opening  left  at  the  center 
with  a  drop  or  two  from  the  welding  rod. 

WELDING    VARIOUS    METALS 

Because  of  the  varying  melting  points,  rates  of 
expansion  and  contraction,  and  other  peculiarities 
of  different  metals,  it  is  necessary  to  give  detailed 
consideration  to  the  most  important  ones. 

Characteristics  of  Metals. — The  welder  should  thor- 
oughly understand  the  peculiarities  of  the  various 


126  WELDING 

metals  with  which  he  has  to  deal.  The  metals  and 
their  alloys  are  described  under  this  heading  in  the 
first  chapter  of  this  book  and  a  tabulated  list  of  the 
most  important  points  relating  to  each  metal  will 
be  found  at  the  end  of  the  present  chapter.  All  this 
information  should  be  noted  by  the  operator  of  a 
welding  installation  before  commencing  actual  work. 

Because  of  the  nature  of  welding,  the  melting 
point  of  a  metal  is  of  great  importance.  A  metal 
melting  at  a  low  temperature  should  have  more  care- 
ful treatment  to  avoid  undesired  flow  than  one  which 
melts  at  a  temperature  which  is  relatively  high. 
When  two  dissimilar  metals  are  to  be  joined,  the 
one  which  melts  at  the  higher  temperature  must  be 
acted  upon  by  the  flame  first  and  when  it  is  in  a 
molten  condition  the  heat  contained  in  it  will  in 
many  cases  be  sufficient  to  cause  fusion  of  the  lower 
melting  metal  and  allow  them  to  unite  without  play- 
ing the  flame  on  the  lower  metal  to  any  great  extent. 

The  heat  conductivity  bears  a  very  important 
relation  to  welding,  inasmuch  as  a  metal  with  a  high 
rate  of  conductance  requires  more  protection  from 
cooling  air  currents  and  heat  radiation  than  one  not 
having  this  quality  to  such  a  marked  extent.  A 
metal  which  conducts  heat  rapidly  will  require  a 
larger  volume  of  flame,  a  larger  nozzle,  than  other- 
wise, this  being  necessary  to  supply  the  additional 
heat  taken  away  from  the  welding  point  by  this 
conductance. 

The  relative  rates  of  expansion  of  the  various 
metals  under  heat  should  be  understood  in  order  that 
parts  made  from  such  material  may  have  proper* 
preparation  to  compensate  for  this  expansion  and 
contraction.  Parts  made  from  metals  having  widely 


OXY-ACETYLENE  WELDING  PRACTICE  127 

varying  rates  of  expansion  must  have  special  treat- 
ment to  allow  for  this  quality,  otherwise  breakage 
is  sure  to  occur. 

Cast  Iron. — All  spoiled  metal  should  be  cut  away 
and  if  the  work  is  more  than  one-eighth  inch  in 
thickness  the  sides  of  the  crack  should  be  beveled 
to  a  45  degree  angle,  leaving  a  number  of  points 
touching  at  the  bottom  of  the  bevel  so  that  the  work 
may  be  joined  in  its  original  relation. 

The  entire  piece  should  be  preheated  in  a  bricked-up 
oven  or  with  charcoal  placed  on  the  forge,  when  size 
does  not  warrant  building  a  temporary  oven.  The 
entire  piece  should  be  slowly  heated  and  the  portion 
immediately  surrounding  the  weld  should  be  brought 
to  a  dull  red.  Care  should  be  used  that  the  heat  does 
not  warp  the  metal  through  application  to  one  part 
more  than  the  others.  After  welding,  the  work 
should  be  slowly  cooled  by  covering  with  ashes, 
slaked  lime,  asbestos  fibre  or  some  other  non-con- 
ductor of  heat.  These  precautions  are  absolutely 
essential  in  the  case  of  cast  iron. 

A  neutral  flame,  from  a  nozzle  proportioned  to  the 
thickness  of  the  work,  should  be  held  with  the  point 
of  the  blue-white  cone  about  one-eighth  inch  from 
the  surface  of  the  iron. 

A  cast  iron  rod  of  correct  diameter,  usually  made 
with  an  excess  of  silicon,  is  used  by  keeping  its  end 
in  contact  with  the  molten  metal  and  flowing  it  into 
the  puddle  formed  at  the  point  of  fusion.  Metal 
should  be  added  so  that  the  weld  stands  about  one- 
eighth  inch  above  the  surrounding  surface  of  the 
work. 

Various  forms  of  flux  may  be  used  and  they  are 
applied  by  dipping  the  end  of  the  welding  rod  into 


128  WELDING 

the  powder  at  intervals.  These  powders  may  con- 
tain borax  or  salt,  and  to  prevent  a  hard,  brittle 
weld,  graphite  or  ferro-silicon  may  be  added.  Flux 
should  be  added  only  after  the  iron  is  molten  and 
as  little  as  possible  should  be  used.  No  flux  should 
be  used  just  before  completion  of  the  work. 

The  welding  flame  should  be  played  on  the  work 
around  the  crack  and  gradually  brought  to  bear  on 
the  work.  The  bottom  of  the  bevel  should  be  joined 
first  and  it  will  be  noted  that  the  cast  iron  tends  to 
run  toward  the  flame,  but  does  not  stick  together 
easily.  A  hard  and  porous  weld  should  be  carefully 
guarded  against,  as  described  above,  and  upon  com- 
pletion of  the  work  the  welded  surface  should  be 
scraped  with  a  file,  while  still  red  hot,  in  order  to 
remove  the  surface  scale. 

Malleable  Iron. — This  material  should  be  beveled 
in  the  same  way  that  cast  iron  is  handled,  and  pre- 
heating and  slow  cooling  are  equally  desirable.  The 
flame  used  is  the  same  as  for  cast  iron  and  so  is  the 
flux.  The  welding  rod  may  be  of  cast  iron,  although 
better  results  are  secured  with  Norway  iron  wire 
or  else  a  mild  steel  wire  wrapped  with  a  coil  of 
copper  wire. 

It  will  be  understood  that  malleable  iron  turns  to 
ordinary  cast  iron  when  melted  and  cooled.  Welds 
in  malleable  iron  are  usually  far  from  satisfactory 
and  a  better  joint  is  secured  by  brazing  the  edges 
together  with  bronze.  The  edges  to  be  joined  are 
brought  to  a  heat  just  a  little  below  the  point  at 
which  they  will  flow  and  the  opening  is  then  quickly 
filled  from  a  rod  of  Tobin  bronze  or  manganese 
bronze,  a  brass  or  bronze  flux  being  used  in  this 
work. 


OXY-ACETYLENE  WELDING  PRACTICE  129 

Wrought  Iron  or  Semi-Steel. — This  metal  should 
be  beveled  and  heated  in  the  same  way  as  described 
for  cast  iron.  The  flame  should  be  neutral,  of  the 
same  size  as  for  steel,  and  used  with  the  tip  of  the 
blue-white  cone  just  touching  the  work.  The  welding 
rod  should  be  of  mild  steel,  or,  if  wrought  iron  is 
to  be  welded  to  steel,  a  cast  iron  rod  may  be  used. 
A  cast  iron  flux  is  well  suited  for  this  work.  It 
should  be  noted  that  wrought  iron  turns  to  ordinary 
cast  iron  if  kept  heated  for  any  length  of  time. 

Steel. — Steel  should  be  beveled  if  more  than  one- 
eighth  inch  in  thickness.  It  requires  only  a  local 
preheating  around  the  point  to  be  welded.  The 
welding  flame  should  be  absolutely  neutral,  without 
excess  of  either  gas.  If  the  metal  is  one-sixteenth 
inch  or  less  in  thickness,  the  tip  of  the  blue-white 
cone  must  be  held  a  short  distance  from  the  surface 
of  the  work;  in  all  other  cases  the  tip  of  this  cone 
is  touched  to  the  metal  being  welded. 

The  welding  rod  may  be  of  mild,  low  carbon  steel 
or  of  Norway  iron.  Nickel  steel  rods  may  be  used 
for  parts  requiring  great  strength,  but  vanadium 
alloys  are  very  difficult  to  handle.  A  very  satis- 
factory rod  is  made  by  twisting  together  two  wires 
of  the  required  material.  The  rod  must  be  kept 
constantly  in  contact  with  the  work  and  should  not 
be  added  until  the  edges  are  thoroughly  melted.  The 
flux  may  or  may  not  be  used.  If  one  is  wanted,  it 
may  be  made  from  three  parts  iron  filings,  six  parts 
borax  and  one  part  sal  ammoniac. 

It  will  be  noticed  that  the  steel  runs  from  the 
flame,  but  tends  to  hold  together.  Should  foaming 
commence  in  the  molten  metal,  it  shows  an  excess  of 
oxygen  and  that  the  metal  is  being  burned. 


130  WELDING 

High  carbon  steels  are  very  difficult  to  handle. 
It  is  claimed  that  a  drop  or  two  of  copper  added  to 
the  weld  will  assist  the  flow,  but  will  also  harden  the 
work.  An  excess  of  oxygen  reduces  the  amount  of 
carbon  and  softens  the  steel,  while  an  excess  of  acety- 
lene increases  the  proportion  of  carbon  and  hardens 
the  metal.  High  speed  steels  may  sometimes  be 
welded  if  first  coated  with  semi-steel  before  welding. 

Aluminum. — This  is  the  most  difficult  of  the  com- 
monly found  metals  to  weld.  This  is  caused  by  its 
high  rate'  of  expansion  and  contraction  and  its  lia- 
bility to  melt  and  fall  away  from  under  the  flame. 
The  aluminum  seems  to  melt  on  the  inside  first,  and, 
without  previous  warning,  a  portion  of  the  work  will 
simply  vanish  from  in  front  of  the  operator's  eyes. 
The  metal  tends  to  run  from  the  flame  and  separate 
at  the  same  time.  To  keep  the  metal  in  shape  and 
free  from  oxide,  it  is  worked  or  puddled  while  in  a 
plastic  condition  by  an  iron  rod  which  has  been  flat- 
tened at  one  end.  Several  of  these  rods  should  be 
at  hand  and  may  be  kept  in  a  jar  of  salt  water  while 
not  being  used.  These  rods  must  not  become  coated 
with  aluminum  and  they  must  not  get  red  hot  while 
in  the  weld. 

The  surfaces  to  be  joined,  together  with  the  adja- 
cent parts,  should  be  cleaned  thoroughly  and  then 
washed  with  a  25  per  cent  solution  of  nitric  acid  in 
hot  water,  used  on  a  swab.  The  parts  should  then 
be  rinsed  in  clean  water  and  dried  with  sawdust. 
It  is  also  well  to  make  temporary  fire  clay  moulds 
back  of  the  parts  to  be  heated,  so  that  the  metal 
may  be  flowed  into  place  and  allowed  to  cool  without 
danger  of  breakage. 

Aluminum  must  invariably  be  preheated  to  about 


OXY-ACETYLENE  WELDING  PRACTICE  131 

600  degrees,  and  the  whole  piece  being  handled 
should  be  well  covered  with  sheet  asbestos  to  prevent, 
excessive  heat  radiation. 

The  flame  is  formed  with  an  excess  of  acetylene 
such  that  the  second  cone  extends  about  an  inch, 
or  slightly  more,  beyond  the  small  blue-white  point. 
The  torch  should  be  held  so  that  the  end  of  this 
second  cone  is  in  contact  with  the  work,  the  small 
cone  ordinarily  used  being  kept  an  inch  or  an  inch 
and  a  half  from  the  surface  of  the  work. 

Welding  rods  of  special  aluminum  are  used  and 
must  be  handled  with  their  end  submerged  in  the 
molten  metal  of  the  weld  at  all  times. 

When  aluminum  is  melted  it  forms  alumina,  an 
oxide  of  the  metal.  This  alumina  surrounds  small 
masses  of  the  metal,  and  as  it  does  not  melt  at  tem- 
peratures below  5000  degrees  (while  aluminum  melts 
at  about  1200),  it  prevents  a  weld  from  being  made. 
The  formation  of  this  oxide  is  retarded  and  the  oxide 
itself  is  dissolved  by  a  suitable  flux,  which  usually 
contains  phosphorus  to  break  down  the  alumina. 

Copper. — The  whole  piece  should  be  preheated  and 
kept  well  covered  while  welding.  The  flame  must  be 
much  larger  than  for  the  same  thickness  of  steel 
and  neutral  in  character.  A  slight  excess  of  acety- 
lene would  be  preferable  to  an  excess  of  oxygen,  and 
in  all  cases  the  molten  metal  should  be  kept  envel- 
oped with  the  flame.  The  welding  rod  is  of  copper 
which  contains  phosphorus;  and  a  flux,  also  contain- 
ing phosphorus,  should  be  spread  for  about  an  inch 
each  side  of  the  joint.  These  assist  in  preventing 
oxidation,  which  is  sure  to  occur  with  heated  copper. 

Copper  breaks  very  easily  at  a  heat  slightly  under 


132  WELDING 

the  welding  temperature  and  after  cooling  it  is  sim- 
ply cast  copper  in  all  cases. 

Brass  and  Bronze. — It  is  necessary  to  preheat  these 
metals,  although  not  to  a  very  high  temperature. 
They  must  be  kept  well  covered  at  all  times  to  pre~ 
vent  undue  radiation.  The  flame  should  be  produced 
with  a  nozzle  one  size  larger  than  for  the  same 
thickness  of  steel  and  the  small  blue-white  cone  should 
be  held  from  one-fourth  to  one-half  inch  above  the 
surface  of  the  work.  The  flame  should  be  neutral 
in  character. 

A  rod  or  wire  of  soft  brass  containing  a  large  per- 
centage of  zinc  is  suitable  for  adding  to  brass,  while 
copper  requires  the  use  of  copper  or  manganese 
bronze  rods.  Special  flux  or  borax  may  be  used  to 
assist  the  flow. 

The  emission  of  white  smoke  indicates  that  the 
zinc  contained  in  these  alloys  is  being  burned  away 
and  the  heat  should  immediately  be  turned  away  or 
reduced.  The  fumes  from  brass  and  bronze  welding 
are  very  poison,ous  and  should  not  be  breathed. 

RESTORATION  OF  STEEL 

The  result  of  the  high  heat  to  which  the  steel  has 
been  subjected  is  that  it  is  weakened  and  of  a  dif- 
ferent character  than  before  welding.  The  operator 
may  avoid  this  as  much  as  possible  by  first  playing 
the  outer  flame  of  the  torch  all  over  the  surfaces 
of  the  work  just  completed  until  these  faces  are  all 
of  uniform  color,  after  which  the  metal  should  be 
well  covered  with  asbestos  and  allowed  to  cool  with- 
out being  disturbed.  If  a  temporary  heating  oven 
has  been  employed,  the  work  and  oven  should  be 
allowed  to  cool  together  while  protected  with  the 


OXY-ACETYLENE  WELDING  PRACTICE  133 

sheet  asbestos.  If  the  outside  air  strikes  tlie  freshly 
welded  work,  even  for  a  moment,  the  result  will  be 
breakage. 

A  weld  in  steel  will  always  leave  the  metal  with 
a  coarse  grain  and  with  all  the  characteristics  of 
rather  low  grade  cast  steel.  As  previously  men- 
tioned in  another  chapter,  the  larger  the  grain  size 
in  steel  the  weaker  the  metal  will  be,  and  it  is  the 
purpose  of  the  good  workman  to  avoid,  as  far  as 
possible,  this  weakening. 

The  structure  of  the  metal  in  one  piece  of  steel 
will  differ  according  to  the  heat  that  it  has  under- 
gone. The  parts  of  the  work  that  have  been  at  the 
melting  point  will,  therefore,  have  the  largest  grain 
size  and  the  least  strength.  Those  parts  that  have 
not  suffered  any  great  rise  in  temperature  will  be 
practically  unaffected,  and  all  the  parts  between 
these  two  extremes  will  be  weaker  or  stronger  accord- 
ing to  their  distance  from  the  weld  itself.  To  restore 
the  steel  so  that  it  will  have  the  best  grain  size,  the 
operator  may  resort  to  either  of  two  methods:  (1) 
The  grain  may  be  improved  by  forging.  That  means 
that  the  metal  added  to  the  weld  and  the  surfaces 
that  have  been  at  the  welding  heat  are  hammered, 
much  as  a  blacksmith  would  hammer  his  finished 
work  to  give  it  greater  strength.  The  hammering 
should  continue  from  the  time  the  metal  first  starts 
to  cool  until  it  has  reached  the  temperature  at  which 
the  grain  size  is  best  for  strength.  This  temperature 
will  vary  somewhat  with  the  composition  of  the  metal 
being  handled,  but  in  a  general  way,  it  may  be  stated 
that  the  hammering  should  continue  without  inter- 
mission from  the  time  the  flame  is  removed  from  the 
weld  until  the  steel  just  begins  to  show  attraction 


134  WELDING 

for  a  magnet  presented  to  it.  This  temperature  of 
magnetic  attraction  will  always  be  low  enough  and 
the  hammering  should  be  immediately  discontinued 
at  this  point.  (2)  A  method  that  is  more  satisfac- 
tory, although  harder  to  apply,  is  that  of  reheating 
the  steel  to  a  certain  temperature  throughout  its 
whole  mass  where  the  heat  has  had  any  effect,  and 
then  allowing  slow  and  even  cooling  from  this  tem- 
perature. The  grain  size  is  affected  by  the  tempera- 
ture at  which  the  reheating  is  stopped  and  not  by 
the  cooling,  yet  the  cooling  should  be  slow  enough  to 
avoid  strains  caused  by  uneven  contraction. 

After  the  weld  has  been  completed  the  steel  must 
be  allowed  to  cool  until  below  1200°  Fahrenheit.  The 
next  step  is  to  heat  the  work  slowly  until  all  those 
parts  to  be  restored  have  reached  a  temperature  at 
which  the  magnet  just  ceases  to  be  attracted.  While 
the  very  best  temperature  will  vary  according  to  the 
nature  and  hardness  of  the  steel  being  handled,  it 
will  be  safe  to  carry  the  heating  to  .the  point  indi- 
cated by  the  magnet  in  the  absence  of  suitable  means 
of  measuring  accurately  these  high  temperatures.  In 
using  a  magnet  for  testing,  it  will  be  most  satisfac- 
tory if  it  is  an  electromagnet  and  not  of  the  perma- 
nent type.  The  electric  current  may  be  secured 
from  any  small  battery  and  will  be  the  means  of 
making  sure  of  the  test.  The  permanent  magnet  will 
quickly  lose  its  power  of  attraction  under  the  com- 
bined action  of  the  heat  and  the  jarring  to  which 
it  will  be  subjected. 

In  reheating  the  work  it  is  necessary  to  make  sure 
that  no  part  reaches  a  temperature  above  that  desired 
for  best  grain  size  and  also  to  see  that  all  parts  are 
brought  to  this  temperature.  Here  enters  the  great- 


OXY-ACETYLENB  WELDING  PRACTICE  135 

est  difficulty  in  restoring  the  metal.  The  heating 
may  be  done  so  slowly  that  no  part  of  the  work  on 
the  outside  reaches  too  high  a  temperature  and  then 
keeps  the  outside  at  this  heat  until  the  entire  mass 
is  at  the  same  temperature.  A  less  desirable  way 
is  to  heat  the  outside  higher  than  this  temperature 
and  allow  the  conductivity  of  the  metal  to  distribute 
the  excess  to  the  inside. 

The  most  satisfactory  method,  where  it  can  be 
employed,  is  to  make  use  of  a  bath  of  some  molten 
metal  or  some  chemical  mixture  that  can  be  kept 
at  the  exact  heat  necessary  by  means  of  gas  fires 
that  admit  of  close  regulation.  The  temperature  of 
these  baths  may  be  maintained  at  a  constant  point 
by  watching  a  pyrometer,  and  the  finished  work  may 
be  allowed  to  remain  in  the  bath  until  all  parts  have 
reached  the  desired  temperature. 

WELDING  INFORMATION 

The  following  tables  include  much  of  the  informa- 
tion that  the  operator  must  use  continually  to  handle 
the  various  metals  successfully.  The  temperature 
scales  are  given  for  convenience  only.  The  composi- 
tion of  various  alloys  will  give  an  idea  of  the  diffi- 
culties to  be  contended  with  by  consulting  the  infor- 
mation on  welding  various  metals.  The  remaining 
tables  are  of  self-evident  value  in  this  work. 


136 


WELDING 


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OXY-ACETYLENE  WELDING  PRACTICE  137 

METAL    ALLOYS 

(Society  of  Automobile  Engineers) 

Babbitt- 
Tin   84.00% 

Antimony    9.00% 

Copper    7.00% 

Brass,  "White — 

Copper    3.00%  to     6.00% 

Tin   (minimum)    65.00% 

Zinc    : .• 28.00%  to  30.00% 

Brass,  Red  Cast — 

Copper  85.00% 

Tin    5.00% 

Lead   5.00% 

Zinc 5.00% 

Brass,  Yellow — 

Copper   62.00%  to  65.00% 

Lead 2.00%  to     4.00% 

Zinc    36.00%  to  31.00% 

Bronze,  Hard — 

Copper    87.00%  to  88.00% 

Tin    9.50%  to  10.50% 

Zinc    1.50%  to     2.50% 

Bronze,  Phosphor — 

Copper 80.00% 

Tin    10.00% 

Lead    10.00% 

Phosphorus 50%  to        .25% 

Bronze,  Manganese — 

Copper    (approximate) ,  60.00% 

Zinc    (approximate) 40.00% 

Manganese   (variable) small 

Bronze,  Gear — 

Copper    88.00%  to  89.00% 

Tin 11.00%  to  12.00% 

Phosphorus    15%  to       .30% 


138 


WELDING 


Copper      Zinc 
8.5-7.0% 
2.0-3.0%     15% 
35.0% 


Manganese 
Not  over  0.40% 


Aluminum  Alloys — 

Aluminum 

No.   1..   90.00% 

No.  2..   80.00% 

No.  3..   65.00% 

Cast  Iron — 

Gray  Iron  Malleable 

Total  carbon   3.0  to  3.5% 

Combined  carbon   ...0.4  to  0.7% 

Manganese    0.4  to  0.7%          0.3  to  0.7% 

Phosphorus   0.6  to  1.0%     Not  over  0.2% 

Sulphur Not  over  0.1%     Not  over  0.6% 

Silicon 1.75  to  2.25%  Not  over  1.0% 

Carbon  Steel  (10  Point)  — 

Carbon 05%  to  .15% 

Manganese   30%  to  .60% 

Phosphorus  (maximum) .045% 

Sulphur  (maximum)    .05% 

(20  Point)  — 

Carbon 15%  to  .25% 

Manganese    30%  to  .60% 

Phosphorus  (maximum) .045% 

Sulphur  (maximum)    .05% 

(35  Point)  — 

Manganese   50%  to  .80% 

Carbon    30%  to  .40% 

Phosphorus  (maximum)    .05% 

Sulphur  (maximum)    .05% 

(95  Point)  — 

Carbon 90%  to  1.05% 

Manganese   25%  to  .50% 

Phosphorus   (maximum)    .04% 

Sulphur ' (maximum)    .05% 


OXY-ACETYLENE  WELDING  PRACTICE  139 

HEATING   POWER   OP   FUEL   GASES 

(In  B.  T.  U.  per  Cubic  Foot.) 

Acetylene    1498.99     Ethylene  1562.95 

Hydrogen 291.96    Methane   953.62 

Alcohol 1501.76 

MELTING    POINTS    OF    METALS 

Platinum    3200° 

Iron,  wrought  2900° 

malleable    2500° 

cast 2400° 

pure    2760° 

Steel,  mild  2700° 

medium    2600° 

hard   2500° 

Copper    1950° 

Brass 1800° 

Silver 1750° 

Bronze ....1700° 

Aluminum    , 1175° 

Antimony    1150° 

Zinc    800° 

Lead    620° 

Babbitt    500-700° 

Solder    500-575° 

Tin   450° 

NOTE. — These  melting  points  are  for  average  com- 
positions and  conditions.  The  exact  proportion  of 
elements  entering  into  the  metals  affects  their  melting 
points  one  way  or  the  other  in  practice. 


140  WELDING 

TENSILE  STRENGTH  OF  METALS 

Alloy  steels  can  be  made  with  tensile  strengths  as 
high  as  300,000  pounds  per  square  inch.  Some  car- 
bon steels  are  given  below  according  to  "points": 

-     Pounds  per  Square  Inch 

Steel,  10  point 50,000  to  65,000 

20  point 60,000  to  80,000 

40  point 70,000  to  100,000 

60  point 90,000  to  120,000 

Iron,  Cast 13,000  to  30,000 

Wrought 40,000  to  60,000 

Malleable    25,000  to  45,000 

Copper    24,000  to  50,000 

Bronze    30,000  to  60,000 

Brass,  Cast 12,000  to  18,000 

Boiled    30,000  to  40,000 

Wire    60,000  to  75,000 

Aluminum    12,000  to  23,000 

Zinc    5,000  to  15,000 

Tin    ; 3,000  to  5,000 

Lead    1,500  to  2,500 

CONDUCTIVITY  OF   METALS 

(Based  on  the  Value  of  Silver  as  100) 

Heat  Electricity 

Silver    100  100 

Copper 74  99 

Aluminum    38  63 

Brass    23  22 

Zinc    19  29 

Tin                                                       14  15 


OXY-ACETYLENE  WELDING  PRACTICE  141 

Heat  Electricity 

Wrought  Iron   12  16 

Steel    11.5  12 

Cast  Iron   11  12 

Bronze    9  7 

Lead    8  9 

WEIGHT  OF  METALS 

(Per  Cubic  Inch) 

Pounds  Pounds 

Lead    410     Wrought   Iron 278 

Copper    320     Tin    263 

Bronze    313     Cast  Iron   260 

Brass    , .   .300     Zinc    258 

Steel    283     Aluminum    093 

EXPANSION   OF  METALS 

(Measured  in  Thousandths  of  an  Inch  per  Foot  of 

Length  When  Raised  1000  Degrees 

in  Temperature) 

Inch  Inch 

Lead    188    Brass  115 

Zinc    168     Copper    106 

Aluminum    148     Steel    .' 083 

Silver   129     Wrought   Iron 078 

Bronze  .118     Cast   Iron..  .068 


CHAPTER  VI 
ELECTEIC  WELDING 
RESISTANCE   METHOD 

Two  distinct  forms  of  electric  welding  apparatus 
are  in  use,  one  producing  heat  by  the  resistance  of  the 
metal  being  treated  to  the  passage  of  electric  cur- 
rent, the  other  using  the  heat  of  the  electric  arc. 

The  resistance  process  is  of  the  greatest  use  in 
manufacturing  lines  where  there  is  a  large  quantity 
of  one  kind  of  work  to  do,  many  thousand  pieces  of 
one  kind,  for  instance.  The  arc  method  may  be  ap- 
plied in  practically  any  case  where  any  other  form 
of  weld  may  be  made.  The  resistance  process  will  be 
described  first. 

It  is  a  well  known  fact  that  a  poor  conductor  of 
electricity  will  offer  so  much  resistance  to  the  flow  of 
electricity  that  it  will  heat.  Copper  is  a  good  con- 
ductor, and  a  bar  of  iron,  a  comparatively  poor  con- 
ductor, wh^n  placed  between  heavy  copper  conductors 
of  a  welder,  becomes  heated  in  attempting  to  carry  the 
large  volume  of  current.  The  degree  of  heat  depends 
on  the  amount  of  current  and  the  resistance  of  the 
conductor. 

In  an  electric  circuit  the  ends  of  two  pieces  of 
metal  brought  together  form  the  point  of  greatest 
resistance  in  the '  electric  circuit,  and  the  abutting 
ends  instantly  begin  to  heat.  The  hotter  this  metal 
becomes,  the  greater  the  resistance  to  the  flow  of  cur- 
rent; consequently,  as  the  edges  of  the  abutting  ends 
heat,  the  current  is  forced  into  the  adjacent  cooler 

142 


ELECTRIC  WELDING 


143 


parts,  until  there  is  a  uniform  heat  throughout  the 
entire  mass.  The  heat  is  first  developed  in  the  inte- 
rior of  the  metal  so  that  it  is  welded  there  as  perfectly 
as  at  the  surface. 


Figure  42. — Spot  Welding  Machine 

The  electric  welder  (Figure  .42)  is  built  to  hold  the 
parts  to  be  joined  between  two  heavy  copper  dies  or 
contacts.  A  current  of  three  to  five  volts,  but  of 
very  great  volume  (amperage),  is  allowed  to  pass 
across  these  dies,  and  in  going  through  the  metal  to 
be  welded,  heats  the  edges  to  a  welding  temperature. 
It  may  be  explained  that  the  voltage  of  an  electric 


144  WELDING 

current  measures  the  pressure  or  force  with  which  it 
is  being  sent  through  the  circuit  and  has  nothing  to 
do  with  the  quantity  or  volume  passing.  Amperes 
measure  the  rate  at  which  the  current  is  passing 
through  the  circuit  and  consequently  give  a  measure 
of  the  quantity  which  passes  in  any  given  time.  Volts 
correspond  to  water  pressure  measured  by  pounds  to 
the  square  inch ;  amperes  represent  the  flow  in  gallons 
per  minute.  The  low  voltage  used  avoids  all  danger 
to  the  operator,  this  pressure  not  being  sufficient  to 
be  felt  even  with  the  hands  resting  on  the  copper 
contacts. 

Current  is  supplied  to  the  welding  machine  at  a 
higher  voltage  and  lower  amperage  than  is  actually 
used  between  the  dies,  the  low  voltage  and  high  am- 
perage being  produced  by  a  transformer  incorporated 
in  the  machine  itself.  By  means  of  windings  of  suit- 
able size  wire,  the  outside  current  may  be  received  at 
voltages  ranging  from  110  to  550  and  converted  to  the 
low  pressure  needed. 

The  source  of  current  for  the  resistance  welder 
must  be  alternating,  that  is,  the  current  must  first  be 
negative  in  value  and  then  positive,  passing  from  one 
extreme  to  the  other  at  rates  varying  from  25  to  133 
times  a  second.  This  form  is  known  as  alternating 
current,  as  opposed  to  direct  current,  in  which  there 
is  no  changing  of  positive  and  negative. 

The  current  must  also  be  what  is  known  as  single 
phase,  that  is,  a  current  which  rises  from  zero  in  value 
to  the  highest  point  as  a  positive  current  and  then 
recedes  to  zero  before  rising  to  the  highest  point  of 
negative  value.  Two-phase  of  three-phase  currents 
would  give  two  or  three  positive  impulses  during  this 
time. 


ELECTRIC  WELDING  145 

As  long  as  the  current  is  single  phase  alternating, 
the  voltage  and  cycles  (number  of  alternations  per 
second)  may  be  anything  convenient.  Various  volt- 
ages and  cycles  are  taken  care  of  by  specifying  all 
these  points  when  designing  the  transformer  which 
is  to  handle  the  current. 

Direct  current  is  not  used  because  there  is  no  way 
of  reducing  the  voltage  conveniently  without  placing 
resistance  wires  in  the  circuit  and  this  uses  power 
without  producing  useful  work.  Direct  current  may 
be  changed  to  alternating  by  having  a  direct  current 
motor  running  an  alternating  current  dynamo,  or 
the  change  may  be  made  by  a  rotary  converter,  al- 
though this  last  method  is  not  so  satisfactory  as  the 
first. 

The  voltage  used  in  welding  being  so  low  to  start 
with,  it  is  absolutely  necessary  that  it  be  maintained 
at  the  correct  point.  If  the  source  of  current  supply 
is  not  of  ample  capacity  for  the  welder  being  used,  it 
will  be  very  hard  to  avoid  a  fall  of  voltage  when  the 
current  is  forced  to  pass  through  the  high  resistance 
of  the  weld.  The  current  voltage  for  various  work  is 
calculated  accurately,  and  the  efficiency  of  the  outfit 
depends  to  a  great  extent  on  the  voltage  being  con- 
stant. 

A  simple  test  for  fall  of  voltage  is  made  by  con- 
necting an  incandescent  electric  lamp  across  the  sup- 
ply lines  at  some  point  near  the  welder.  The  lamp 
should  burn  with  the  same  brilliancy  when  the  weld  is 
being  made  as  at  any  other  time.  If  the  lamp  burns 
dim  at  any  time,  it  indicates  a  drop  in  voltage,  and 
this  condition  should  be  corrected. 

The  dynamo  furnishing  the  alternating  current 
may  be  in  the  same  building  with  the  welder  and 


146  WELDING 

operated  from  a  direct  current  motor,  as  mentioned 
above,  or  operated  from  any  convenient  shafting  or 
source  of  power.  When  the  dynamo  is  a  part  of  the 
welding  plant  it  should  be  placed  as  close  to  the 
welding  machine  as  possible,  because  the  length  of 
the  wire  used  affects  the  voltage  appreciably. 

In  order  to  hold  the  voltage  constant,  the  Toledo 
Electric  Welder  Company  has  devised  connections 
which  include  a  rheostat  to  insert  a  variable  resist- 
ance in  the  field  windings  of  the  dynamo  so  that  the 
voltage  may  be  increased  by  cutting  this  resistance 
out  at  the  proper  time.  An  auxiliary  switch  is  con- 
nected to  the  welder  switch  so  that  both  switches  act 
together.  When  the  welder  switch  is  closed  in  mak- 
ing a  weld,  that  portion  of  the  rheostat  resistance 
between  two  arms  determining  the  voltage  is  short 
circuited.  This  lowers  the  resistance  and  the  field 
magnets  of  the  dynamo  are  made  stronger  so  that 
additional  voltage  is  provided  to  care  for  the  re- 
sistance in  the  metal  being  heated. 

A  typical  machine  is  shown  in  the  accompanying 
cut  (Figure  43).  On  top  of  the  welder  are  two  jaws 
for  holding  the  ends  of  the  pieces  to  be  welded.  The 
lower  part  of  the  jaws  is  rigid  while  the  top  is 
brought  down  on  top  of  the  work,  acting  as  a  clamp. 
These  jaws  carry  the  copper  dies  through  which  the 
current  enters  the  work  being  handled.  After  the 
work  is  clamped  between  the  jaws,  the  upper  set 
is  forced  closer  to  the  lower  set  by  a  long  com- 
pression lever.  The  current  being  turned  on  with 
the  surfaces  of  the  work  in  contact,  they  immedi- 
ately heat  to  the  welding  point  when  added  pressure 
on  the  lever  forces  them  together  and  completes  the 
weld. 


ELECTRIC  WELDING 


147 


148  WELDING 


The  transformer  is  carried  in  the  base  of  the  ma- 
chine and  on  the  left-hand  side  is  a  regulator  for 
controlling  the  voltage  for  various  kinds  of  work.  The 
clamps  are  applied  by  treadles  convenient  to  the  foot 


Figure  43a. — Method  of  Testing  Electric  Welder 

of  the  operator.  A  treadle  is  provided  which  instantly 
releases  both  jaws  upon  the  completion  of  the  weld. 


Figure  44. — Detail  of  Water-Cooled  Spot  Welding  Head 

One  or  both  of  the  copper  dies  may  be  cooled  by  a 
stream  of  water  circulating  through  it  from  the  city 
water  mains  (Figure  44).  The  regulator  and  switch 
give  the  operator  control  of  the  heat,  anything  from 


ELECTRIC  WELDING 


149 


a  dull  red  to  the  melting  point  being  easily  obtained 
by  movement  of  the  lever  (Figure  45). 

Welding. — It  is  not  necessary  to   give  the  metal ' 
to  be  welded  any  special  preparation,  although  when 
very  rusty  or  covered  with  scale,  the  rust  and  scale 


Figure  45. — Welding  Head  of  a  Water-Cooled  Welder 

should  be  removed  sufficient^  to  allow  good  contact 
of  clean  metal  on  the  copper  dies.  The  cleaner  and 
better  the  stock,  the  less  current  it  takes,  and  there 
is  less  wear  on  the  dies.  The  dies  should  be  kept 
firm  and  tight  in  their  holders  to  make  a  good  contact. 
All  bolts  and  nuts  fastening  the  electrical  contacts 
should  be  clean  and  tight  at  all  times. 


150  WELDING 

The  scale  may  be  removed  from  forcings  by  im- 
mersing them  in  a  pickling  solution  in  a  wood,  stone 
or  lead-lined  tank. 

The  solution  is  made  with  five  gallons  of  commer- 
cial sulphuric  acid  in  150  gallons  of  water.  To  get 
the  quickest  and  best  results  from  this  method,  the 
solution  should  be  kept  as  near  the  boiling  point  as 
possible  by  having  a  coil  of  extra  heavy  lead  pipe 
running  inside  the  tank  and  carrying  live  steam.  A 
very  few  minutes  in  this  bath  will  remove  the  scale 
and  the  parts  should  then  be  washed  in  running 
water.  After  this  washing  they  should  be  dipped  into 
a  bath  of  50  pounds  of  unslaked  lime  in  150  gallons 
of  water  to  neutralize  any  trace  of  acid. 

Cast  iron  cannot  be  commercially  welded,  as  it  is 
high  in  carbon  and  silicon,  and  passes  suddenly  from 
a  crystalline  to  a  fluid  state  when  brought  to  the  weld- 
ing temperature.  With  steel  or  wrought  iron  the 
temperature  must  be  kept  below  the  melting  point  to 
avoid  injury  to  the  metal.  The  metal  must  be  heated 
quickly  and  pressed  together  with  sufficient  force  to 
push  all  burnt  metal  out  of  the  joint. 

High  carbon  steel  can  be  welded,  but  must  be  an- 
nealed after  welding  to  overcome  the  strains  set  up 
by  the  heat  being  applied  at  one  place.  Good  results 
are  hard  to  obtain  when  the  carbon  runs  as  high  as 
75  points,  and  steel  of  this  class  can  only  be  handled 
by  an  experienced  operator.  If  the  steel  is  below  25 
points  in  carbon  content,  good  welds  will,  always  be 
the  result.  To  weld  high  carbon  to  low  carbon  steel, 
the  stock  should  be  clamped  in  the  dies  with  the  low 
carbon  stock  sticking  considerably  further  out  from 
the  die  than  the  high  carbon  stock.  Nickel  steel  welds 
readily,  the  nickel  increasing  the  strength  of  the  weld. 


ELECTRIC  WELDING  151 

Iron  and  copper  may  be  welded  together  by  reduc; 
ing  the  size  of  the  copper  end  where  it  comes  in  con- 
tact with  the  iron.  When  welding  copper  and  brass 
the  pressure  must  be  less  than  when  welding  iron. 
The  metal  is  allowed  to  actually  fuse  or  melt  at  the 
juncture  and  the  pressure  must  be  sufficient  to  force 
the  burned  metal  out.  The  current  is  cut  off  the 
instant  the  metal  ends  begin  to  soften,  this  being 
done  by  means  of  an  automatic  switch  which  opens 
when  the  softening  of  the  metal  allows  the  ends  to 
come  together.  The  pressure  is  applied  to  the  weld 
by  having  the  sliding  jaw  moved  by  a  weight  on  the 
end  of  an  arm. 

Copper  and  brass  require  a  larger  volume  of  cur- 
rent at  a  lower  voltage  than  for  steel  and  iron.  The 
die  faces  are  set  apart  three  times  the  diameter  o£ 
the  stock  for  "brass  and  four  times  the  diameter  for 
copper. 

Light  gauges  of  sheet  steel  can  be  welded  to  heavy 
gauges  or  to  solid  bars  of  steel  by  "spot"  welding, 
which  will  be  described  later.  Galvanized  iron  can. 
be  welded,  but  the  zinc  coating  will  be  burned  off. 
Sheet  steel  can  be  welded  to  cast  iron,  but  will  pull 
apart,  tearing  out  particles  of  the  iron. 

Sheet  copper  and  sheet  brass  may  be  welded,  al- 
though this  work  requires  more  experience  than  with 
iron  and  steel.  Some  grades  of  sheet  aluminum  -can 
be  spot-welded  if  the  slight  roughness  left  on  the  sur- 
face under  the  die  is  not  objectionable. 

Butt  Welding. — This  is  the  process  which  joins  the 
ends  of  two  pieces  of  metal  as  described  in  the  fore- 
going part  of  this  chapter.  The  ends  are  in  plain 
sight  of  the  operator  at  all  times  and  it  can  easily  be 
seen  when  the  metal  reaches  the  welding  heat  and 


152 


WELDING 


begins  to  soften  (Figure  46).  It  is  at  this  point 
that  the  pressure  must  be  applied  with  the  lever  and 
the  ends  forced  together  in  the  weld. 

The  parts  are  placed  in  the  clamping  jaws  (Figure 
47)  with  y$  to  y%  inch  of  metal  extending  beyond  the 


Figure  46. — Butt  Welder 

jaw.  The  ends  of  the  metal  touch  each  other  and 
the  current  is  turned  on  by  means  of  a  switch.  To 
raise  the  ends  to  the  proper  heat  requires  from  3 
seconds  for  34 -inch  rods  to  35  seconds  for  a  l-5/2-inch 
bar. 

This  method  is  applicable  to  metals  having  prac- 
tically the  same  area  of  metal  to  be  brought  into  con- 
tact on  each  end.  When  such  parts  are  forced  to- 


ELECTRIC  WELDING 


153 


gether  a  slight  projection  will  be  left  in  the  form 
of  a  fin  or  an  enlarged  portion  called  an  upset.  The 
degree  of  heat  required  for  any  work  is  found  by 
moving  the  handle  of  the  regulator  one  way  or  the 
other  while  testing  several  parts.  When  this  setting 


Figure  47. — Clamping  Dies  of  a  Butt  Welder 

is  right  the  work  can  continue  as  long  as  the  same 
sizes  are  being  handled. 

Copper,  brass,  tool  steel  and  all  other  metals  that 
are  harmed  by  high  temperatures  must  be  heated 
quickly  and  pressed  together  with  sufficient  force  to 
force  all  burned  metal  from  the  weld. 

In  case  it  is  desired -to  make  a  weld  in  the  form 
of  a  capital  letter  T,  it  is  necessary  to  heat  the  part 
corresponding  to  the  top  bar  of  the  T  to  a  bright  red, 
then  bring  the  lower  bar  to  the  pre-heated  one  and 


154  WELDING 

again   turn   on   the   current,    when    a   weld   can   be 
quickly  made. 

Spot  Welding. — This  is  a  method  of  joining  metal 
sheets  together  at  any  desired  point  by  a  welded  spot 
about  the  size  of  a  rivet.  It  is  done  on  a  spot  welder 
by  fusing  the  metal  at  the  point  desired  and  at  the 
same  instant  applying  sufficient  pressure  to  force  the 
particles  of  molten  metal  together.  The  dies  are  usu- 
ally placed  one  above  the  other  so  that  the  work  may 
rest  on  the  lower  one  while  the  upper  one  is  brought 
down  on  top  of  the  upper  sheet  to  be  welded. 

One  of  the  dies  is  usually  pointed  slightly,  the  op- 
posing one  being  left  flat.  The  pointed  die  leaves  a 
slight  indentation  on  one  side  of  the  metal,  while  the 
other  side  is  left  smooth.  The  dies  may  be  reversed 
so  that  the  outside  surface  of  any  work  may  be  left 
smooth.  The  current  is  allowed  to  flow  through  the 
dies  by  a  switch  which  is  closed  after  pressure  is 
applied  to  the  work. 

There  is  a  limit  to  the  thickness  of  sheet  metal  that 
can  be  welded  by  this  process  because  of  the  fact 
that  the  copper  rods  can  only  carry  a  certain  quantity 
of  current  without  becoming  unduly  heated  them- 
selves. Another  reason  is  that  it  is  difficult  to  make 
heavy  sections  of  metal  touch  at  the  welding  point 
without  excessive  pressure. 

Lap  welding  is  the  process  used  when  two  pieces  of 
metal  are  caused  to  overlap  and  when  brought  to  a 
welding  heat  are  forced  together  by  passing  through 
rollers,  or  under  a  press,  thus  leaving  the  welded  joint 
practically  the  same  thickness  as  the  balance  of  the 
work. 

Where  it  is  desirable  to  make  a  continuous  seam,  a 
special  machine  is  required,  or  an  attachment  for 


ELECTRIC  WELDING  155 

one  of  the  other  types.  In  this  form  of  work  the 
stock  must  be  thoroughly  cleaned  and  is  then  passed 
between  copper  rollers  which  act  in  the  same  capacity 
as  the  copper  dies. 

Other  Applications. — Hardening  and  tempering  can 
be  done  by  clamping  the  work  in  the  welding  dies  and 
setting  the  control  and  time  to  bring  the  metal  to  the 
proper  color,  when  it  is  cooled  in  the  usual  manner. 

Brazing  is  done  by  clamping  the  work  in  the  jaws 
and  heating  until  the  flux,  then  the  spelter  has  melted 
and  run  into  the  joint.  Riveting  and  heading  of 
rivets  can  be  done  by  bringing  the  dies  down  on  oppo- 
site ends  of  the  rivet  after  it  has  been  inserted  in 
the  hole,  the  dies  being  shaped  to  form  the  heads 
properly. 

Hardened  steel  may  be  softened  and  annealed  so 
that  it  can  be  machined  by  connecting  the  dies  of 
the  welder  to  each  side  of  the  point  to  be  softened. 
The  current  is  then  applied  until  the  work  has 
reached  a  point  at  which  it  will  soften  when  cooled.  / 

Troubles  and  Remedies. — The  following  methods 
have  been  furnished  by  the  Toledo  Electric  Welde.r 
Company  and  are  recommended  for  this  class  of  work 
whenever  necessary. 

To  locate  grounds  in  the  primary  or  high  voltage 
side  of  the  circuit,  connect  incandescent  lamps  in 
series  by  means  of  a  long  piece  of  lamp  cord,  as  shown, 
in  Figure  43a.  For  110  volts  use  one  lamp,  for 
220  volts  use  two  lamps  and  for  440  volts  use  four 
lamps.  Attach  one  end  of  the  lamp  cord  to  one  side 
of  the  switch,  and  close  the  switch.  Take  the  other 
end  of  the  cord  in  the  hand  and  press  it  against 
some  part  of  the  welder  frame  where  the  metal  is 
clean  and  bright.  Paint,  grease  and  dirt  act  as  in- 


156  WELDING 

sulators  and  prevent  electrical  contact.  If  the  lamp 
lights,  the  circuit  is  in  electrical  contact  with  the 
frame;  in  other  words,  grounded.  If  the  lamps  do 
not  light,  connect  the  wire  to  a  terminal  block,  die  or 
slide.  If  the  lamps  then  light,  the  circuit,  coils  or 
leads  are  in  electrical  contact  with  the  large  coil  in 
the  transformer  or  its  connections. 

If,  however,  the  lamps  do  not  light  in  either  case, 
the  lamp  cord  should  be  disconnected  from  the  switch 
and  connected  to  the  other  side,  and  the  operations 
of  connecting  to  welder  frame,  dies,  terminal  blocks, 
etc.,  as  explained  above,  should  be  repeated.  If  the 
lamps  light  at  any  of  these  connections,  a  "ground" 
is  indicated.  "Grounds"  can  usually  be  found  by 
carefully  tracing  the  primary  circuit  until  a  place 
is  found  \yhere  the  insulation  is  defective.  Reinsulate 
and  make  the  above  tests  again  to  make  sure  every- 
thing is  clear.  If  the  ground  can  not  be  located  by 
observation,  the  various  parts  of  the  primary  circuit 
should  be  disconnected,  and  the  transformer,  switch, 
regulator,  etc.,  tested  separately. 

.  To  locate  a  ground  in  the  regulator  or  other  part, 
disconnect  the  lines  running  to  the  welder  from  the 
switch.  The  test  lamps  used  in  the  previous  tests  are 
connected,  one  end  of  lamp  cord  to  the  switch,  the 
other  end  to  a  binding  post  of  the  regulator.  Connect 
the  other  side  of  the  switch  to  some  part  of  the  regu- 
lator housing.  (This  must  be  a  clean  connection  to 
a  bolt  head  or  the  paint  should  be  scraped  off.)  Close 
the  switch.  If  the  lamps  light,  the  regulator  winding 
or  some  part  of  the  switch  is  "grounded"  to  the  iron 
base  or  core  of  the  regulator.  If  the  lamps  do  not 
light,  this  part  of  the  apparatus  is  clear. 

This  test  can  be  easily  applied  to  any  part  of  the 


ELECTRIC  WELDING  157 

welder  outfit  by  connecting  to  the  current  carrying 
part  of  the  apparatus,  and  to  the  iron  base  or  frame 
that  should  not  carry  current.  If  the  lamps  light,  it 
indicates  that  the  insulation  is  broken  down  or  is 
defective. 

An  A.  C.  voltmeter  can,  of  course,  be  substituted 
for  the  lamps,  or  a  D.  C.  voltmeter  with  D.  C.  cur- 
rent can  be  used  in  making  the  tests. 

A  short  circuit  in  the  primary  is  caused  by  the  in- 
sulation of  the  coils  becoming  defective  and  allow- 
ing the  bare  copper  wires  to  touch  each  other.  This 
may  result  in  a  "burn  out"  of  one  or  more  of  the 
transformer  coils,  if  the  trouble  is  in  the  transformer, 
or  in  the  continued  blowing  of  fuses  in  the  line.  Feel 
of  each  coil  separately.  If  a  short  circuit  exists  in  a 
coil  it  will  heat  excessively.  Examine  all  the  wires ; 
the  insulation  may  have  worn  through  and  two  of 
them  may  cross,  or  be  in  contact  with  the  frame  or 
other  part  of  the  welder.  A  short  circuit  in  the  regu- 
lator winding  is  indicated  by  failure  of  the  apparatus 
to  regulate  properly,  and  sometimes,  though  not  al- 
ways, by  the  heating  of  the  regulator  coils 

The  remedy  for  a  short  circuit  is  to  reinsulate  the 
defective  parts.  It  is  a  good  plan  to  prevent  trouble 
by  examining  the  wiring  occasionally  and  see  that  the 
insulation  is  perfect. 

To  Locate  Grounds  and  Short  Circuits  in  the 
Secondary,  or  Low  Voltage  Side. — Trouble  of  this 
kind  is  indicated  by  the  machine  acting  sluggish  or, 
perhaps,  refusing  to  operate.  To  make  a  test,  it  will 
be  necessary  to  first  ascertain  the  exciting  current  of 
your  particular  transformer.  This  is  the  current  the 
transformer  draws  on  ( '  open  circuit, ' '  or  when  sup- 
plied with  current  from  the  line  with  no  stock  in 


158  WELDING 


the  welder  dies.     The  following  table  will  give  this 
information  close  enough  for  all  practical  purposes: 


-LV.   VV  . 

Rating 

110  Volts 

220  Volts 

440  Volts 

550  Volts 

3 

1.5 

.75 

.38 

.3 

5 

2.5 

1.25 

.63 

.5 

8 

3.6 

1.8 

.9 

.72 

10 

4.25 

2.13 

1.07 

.85 

15 

6. 

3. 

1.5 

1.2 

20 

7. 

3.5 

1.75 

1.4 

30 

9. 

4.5 

2.25 

1.8 

35 

9.6 

4.8 

2.4 

1.92 

50 

10. 

5. 

2.5 

2. 

Remove  the  fuses  from  the  wall  switch  and  substi- 
tute fuses  just  large  enough  to  carry  the  "  exciting '"' 
current.  If  no  suitable  fuses  are  at  hand,  fine  strands 
of  copper  from  an  ordinary  lamp  cord  may  be  used. 
These  strands  are  usually  No.  30  gauge  wire  and  will 
fuse  at  about  10  amperes.  One  or  more  strands 
should  be  used,  depending  on  the  amount  of  exciting 
current,  and  are  connected  across  the  fuse  clips  in 
place  of  fuse  wire.  Place  a  piece  of  wood  or  fibre 
between  the  welding  dies  in  the  welder  as  though 
you  were  going  to  weld  them.  See  that  the  regulator 
is  on  the  highest  point  and  close  the  welder  switch. 
If  the  secondary  circuit  is  badly  grounded,  current 
will  flow  through  the  ground,  and  the  small  fuses  or 
small  strands  of  wire  will  burn  out.  This  is  an  indi- 
cation that  both  sides  of  the  secondary  circuit  are 
grounded  or  that  a  short  circuit  exists  in  a  primary 
coil.  In  either  case  the  welder  should  not  be  oper- 
ated until  the  trouble  is  found  and  removed.  If, 
however,  the  small  fuses  do  not  "blow/7  remove  same 


ELECTRIC  WELDING  159 

and  replace  the  large  fuses,  then  disconnect  wires 
running  from  the  wall  switch  to  the  welder  and  sub- 
stitute two  pieces  of  No.  8  or  No.  6  insulated  copper 
wire,  after  scraping  off  the  insulation  for  an  inch  or 
two  at  each  end.  Connect  one  wire  from  the  switch  to 
the  frame  of  welder;  this  will  leave  one  loose  end. 
Hold  this  a  foot  or  so  away  from  the  place  where 
the  insulation  is  cut  off ;  then  turn  on  the  current  and 
strike  the  free  end  of  this  wire  lightly  against  one  of 
the  copper  dies,  drawing  it  away  quickly.  If  no 
sparking  is  produced,  the  secondary  circuit  is  free 
from  ground,  and  you  will  then  look  for  a  broken 
connection  in  the  circuit.  Some  caution  must  be 
used  in  making  the  above  test,  as  in  case  one  terminal 
is  heavily  grounded  the  testing  wire  may  be  fused  if 
allowed  to  stay  in  contact  with  the  die. 

The  Remedy. — Clean  the  slides,  dies  and  terminal 
blocks  thoroughly  and  dry  out  the  fibre  insulation  if 
it  is  damp.  See  that  no  scale  or  metal  has  worked 
under  the  sliding  parts,  and  that  the  secondary  leads 
do  not  touch  the  frame.  If  the  ground  is  very  heavy 
it  may  be  necessary  to  remove  the  slides  in  order  to 
facilitate  the  examination  and  removal  of  the  ground. 
Insulation,  where  torn  or  worn  through,  must  be  care- 
fully replaced  or  taped.  If  the  transformer  coils  are 
grounded  to  the  iron  core  of  the  transformer  or  to 
the  secondary,  it  may  be  necessary  to  remove  the  coils 
and  reinsulate  them  at  the  points  of  contact.  A  short 
circuited  coil  will  heat  excessively  and  eventually 
burn  out.  This  may  mean  a  new  coil  if  you  are  unable 
to  repair  the  old  one.  In  all  cases  the  transformer 
windings  should  be  protected  from  mechanical  injury 
or  dampness.  Unless  excessively  overloaded,  trans- 
formers will  last  for  years  without  giving  a  moment 's 


160  WELDING 

trouble,  if  they  are  not  exposed  to  moisture  or  are 
not  injured  mechanically. 

The  most  common  trouble  arises  from  poor  electrical 
contacts,  and  they  are  the  cause  of  endless  trouble  and 
annoyance.  See  that  all  connections  are  clean  and 
bright.  Take  out  the  dies  every  day  or  two  and  see 
that  there  is  no  scale,  grease  or  dirt  between  them 
and  the  holders.  Clean  them  thoroughly  before  re- 
placing. Tighten  the  bolts  running  from  the  trans- 
former leads  to  the  work  jaws. 

ELECTRIC  ARC  WELDING 

This  method  bears  no  relation  to  the  one  just  con- 
sidered, except  that  the  source  of  heat  is  the  same  in 
both  cases.  Arc  welding  makes  use  of  the  flame 
produced  by  the  voltaic  arc  in  practically  the  same 
way  that  oxy-acetylene  welding  uses  the  flame  from 
the  gases. 

If  the  ends  of  two  pieces  of  carbon  through  which  a 
current  of  electricity  is  flowing  while  they  are  in  con- 
tact are  separated  from  each  other  quite  slowly,  a 
brilliant  arc  of  flame  is  formed  between  them  which 
consists  mainly  of  carbon  vapor.  The  carbons  are 
consumed  by  combination  with  the  oxygen  in  the  air 
and  through  being  turned  to  a  gas  under  the  intense 
heat. 

The  most  intense  action  takes  place  at  the  center  of 
the  carbon  which  carries  the  positive  current  and  this 
is  the  point  of  greatest  heat.  The  temperature  at  this 
point  in  the  arc  is  greater  than  can  be  produced  by 
any  other  means  under  human  control. 

An  arc  may  be  formed  between  pieces  of  metal, 
called  electrodes,  in  the  same  way  as  between  carbon. 


ELECTRIC   WELDING  161 


The  metallic  arc  is  called  a  flaming  arc  and  as  the 
metal  of  the  electrode  burns  with  the  heat,  it  gives  the 
flame  a  color  characteristic  of  the  material  being  used. 
The  metallic  arc  may  be  drawn  out  to  a  much  greater 
length  than  one  formed  between  carbon  electrodes. 

Arc  welding  is  carried  out  by  drawing  a  piece  of 
carbon  which  is  of  negative  polarity  away  from  the 
pieces  of  metal  to  be  welded  while  the  metal  is  made 
positive  in  polarity.  The  negative  wire  is  fastened 
to  the  carbon  electrode  and  the  work  is  laid  on  a 
table  made  of  cast  or  wrought  iron  to  which  the  posi- 
tive wire  is  made  fast.  The  direction  of  the  flame  is 
then  from  the  metal  being  welded  to  the  carbon  and 
the  work  is  thus  prevented  from  being  saturated 
with  carbon,  which  would  prove  very  detrimental  to 
its  strength.  A  secondary  advantage  is  found  in  the 
fact  that  the  greatest  heat  is  at  the  metal  being  welded 
because  of  its  being  the  positive  electrode. 

The  carbon  electrode  is  usually  made  from  one 
quarter  to  one  and  a  half  inches  in  diameter  and  from 
six  to  twelve  inches  in  length.  The  length  of  the  arc 
may  be  anywhere  from  one  inch  to  four  inches,  de- 
pending on  the  size  of  the  work  being  handled. 

While  the  parts  are  carefully  insulated  to  avoid 
danger  of  shock,  it  is  necessary  for  the  operator  to 
wear  rubber  gloves  as  a  further  protection,  and  to 
wear  some  form  of  hood  over  the  head  to  shield  him 
against  the  extreme  heat  liberated.  This  hood  may 
be  made  from  metal,  although  some  material  that  does 
not  conduct  electricity  is  to  be  preferred.  The  work 
is  watched  through  pieces  of  glass  formed  with  one 
sheet,  which  is  either  blue  or  green,  placed  over  an- 
other which  is  red.  Screens  of  glass  are  sometimes 
used  without  the  head  protector.  Some  protection  , 


162  WELDING 

for  the  eyes  is  absolutely  necessary  because  of  the 
intense  white  light. 

It  is  seldom  necessary  to  preheat  the  work  as  with 
the  gas  processes,  because  the  heat  is  localized  at  the 
point  of  welding  and  the  action  is  so  rapid  that  the 
expansion  is  not  so  great.  The  necessity  of  pre- 
heating, however,  depends  entirely  on  the  material, 
form  and  size  of  the  work  being  handled.  The  same 
advice  applies  to  arc  welding  as  to  the  gas  flame 
method  but  in  a  lesser  degree.  Filling  rods  are  used 
in  the  same  way  as  with  any  other  flame  process. 

It  is  the  purpose  of  this  explanation  to  state  the 
fundamental  principles  of  the  application  of  the  elec- 
tric arc  to  welding  metals,  and  by  applying  the  prin- 
ciples the  following  questions  will  be  answered : 

What  metals  can  be  welded  by  the  electric  arc? 

"What  difficulties  are  to  be  encountered  in  applying 
the  electric  arc  to  welding? 

What  is  the  strength  of  the  weld  in  comparison  with 
the  original  piece? 

What  is  the  function  of  the  arc  welding  machine 
itself? 

What  is  the  comparative  application  of  the  electric 
arc  and  the  oxy-acetylene  method  and  others  of  a 
similar  nature  ? 

The  answers  to  these  questions  will  make  it  possi- 
ble to  understand  the  application  of  this  process  to 
any  work.  In  a  great  many  places  the  use  of  the  arc 
is  cutting  the  cost  of  welding  to  a  very  small  frac- 
tion of  what  it  would  be  by  any  other  method,  so 
that  the  importance  of  this  method  may  be  well  un- 
derstood. 

Any  two  metals  which  are  brought  to  the  melting 
temperature  and  applied  to  each  other  will  adhere  so 


ELECTRIC  WELDING  f  163 

that  they  are  no  more  apt  to  break  at  the  weld  than 
at  any  other  point  outside  of  the  weld.  It  is  the 
property  of  all  metals  to  stick  together  under  these 
conditions.  The  electric  arc  is  used  in  this  connec- 
tion merely  as  a  heating  agent.  This  is  its  only  func- 
tion in  the  process. 

It  has  advantages  in  its  ease  of  application  and  the 
cheapness  with  which  heat  can  be  liberated  at  any 
given  point  by  its  use.  There  is  nothing  in  connec- 
tion with  arc  welding  that  the  above  principles  will 
not  answer;  that  is,  that  metals  at  the  melting  point 
will  weld  and  that  the  electric  arc  will  furnish  the 
heat  to  bring  them  to  this  point.  As  to  the  first  ques- 
tion, wrhat  metals  can  be  welded,  all  metals  can  be 
welded. 

The  difficulties  which  are  encountered  are  as  fol- 
lows : 

In  the  case  of  brass  or  zinc,  the  metals  will  be  cov- 
ered with  a  coat  of  zinc  oxide  before  they  reach  a 
welding  heat.  This  Zinc  oxide  makes  it  impossible  for 
two  clean  surfaces  to  come  together  and  some  method 
has  to  be  used  for  eliminating  this  possibility  and 
allowing  the  two  surfaces  to  join  without  the  possi- 
bility of  the  oxide  intervening.  The  same  is  true  of 
aluminum,  in  which  the  oxide,  alumina,  will  be 
formed,  and  with  several  other  alloys  comprising  ele- 
ments of  different  melting  points. 

In  order  to  eliminate  these  oxides,  it  is  necessary 
in  practical  work,  to  puddle  the  weld ;  this  is,  to  have 
a  sufficient  quantity  of  molten  metal  at  the  weld  so 
that  the  oxide  is  floated  away.  When  this  is  done, 
the  two  surfaces  which  are  to  be  joined  are  covered 
with  a  coat  of  melted  metal  on  which  floats  the  oxide 
and  other  impurities.  The  two  pieces  are  thus  allowed 


164  WELDING 

to  join  while  their  surfaces  are  protected.  This  pre- 
caution is  not  necessary  in  working  with  steel  except 
in  extreme  cases. 

Another  difficulty  which  is  met  with  in  the  welding 
of  a  great  many  metals  is  their  expansion  under  heat, 
which  results  in  so  great  a  contraction  when  the  weld 
cools  that  the  metal  is  left  with  a  considerable  strain 
on  it.  In  extreme  cases  this  will  result  in  cracking 
at  the  weld  or  near  it.  To  eliminate  this  danger  it 
is  necessary  to  apply  heat  either  all  over  the  piece  to 
be  welded  or  at  certain  points.  In  the  case  of  cast 
iron  and  sometimes  with  copper  it  is  necessary  to 
anneal  after  welding,  since  otherwise  the  welded 
pieces  will  be  very  brittle  on  account  of  the  chilling. 
This  is  also  true  of  malleable  iron. 

Very  thin  metals  which  are  welded  together  and 
are  not  backed  up  by  something  to  carry  away  the 
excess  heat,  are  very  apt  to  burn  through,  leaving  a 
hole  where  the  weld  should  be.  This  difficulty  can 
be  eliminated  by  backing  up  the  weld  with  a  metal 
face  or  by  decreasing  the  intensity  of  the  arc  so  that 
this  melting  through  will  not'  occur.  However,  the 
practical  limit  for  arc  welding  without  backing  up 
the  work  with  a  metal  face  or  decreasing  the  intensity 
of  the  arc  is  approximately  22  gauge,  although  thin-k 
ner  metal  can  be  welded  by  a  very  skillful  and  care- 
ful operator.  , 

One  difficulty  with  arc  welding  is  the  lack  of  skill- 
ful operators.  This  method  is  often  looked  upon  as 
being  something  out  of  the  ordinary  and  governed  by 
laws  entirely  different  from  other  welding.  As  a 
matter  of  fact,  it  does  not  take  as  much  skill  to  make 
a  good  arc  weld  as  it  does  to  make  a  good  weld  in  a 
forge  fire  as  the  blacksmith  does  it.  There  are  few 


ELECTRIC  WELDING  165 

jobs  which  cannot  be  handled  successfully  by  an  oper- 
ator of  average  intelligence  with  one  week's  instruc- 
tions, although  his  work  will  become  better  and  better 
in  quality  as  he  continues  to  use  the  arc. 

Now  comes  the  question  of  the  strength  of  the  weld 
after  it  has  been  made.  This  strength  is  equally  as 
great  as  that  of  the  metal  that  is  used  to  make  the 
weld.  It  should  be  remembered,  however,  that  the 
metal  which  goes  into  the  weld  is  put  in  there  as  a 
casting  and  has  not  been  rolled.  This  would  make 
the  strength  of  the  weld  as  great  as  the  same  metal 
that  is  used  for  filling  if  in  the  cast  form. 

Two  pieces  of  steel  could  be  welded  together  hav- 
ing a  tensile  strength  at  the  weld  of  50,000  pounds. 
Higher  strengths  than  this  can  be  obtained  by  the 
use  of  special  alloys  for  the  filling  material  or  by 
rolling.  Welds  with  a  tensile  strength  as  great  as 
mentioned  will  give  a  result  which  is  perfectly  satis- 
factory in  almost  all  cases. 

There  are  a  great  many  jobs  where  it  is  possible  to 
fill  up  the  weld,  that  is,  make  the  section  at  the  point 
of  the  weld  a  little  larger  than  the  section  through  the 
the  rest  of  the  piece.  By  doing  this,  the  disadvantages 
of  the  weld  being  in  the  form  of  a  casting  in  compari- 
son with  the  rest  of  the  piece  being  in  the  form  of* 
rolled  steel  can  be  overcome,  and  make  the  weld  itself 
even  stronger  than  the  original  piece. 

The  next  question  is  the  adaptability  of  the  electric 
arc  in  comparison  with  forge  fire,  oxy-acetylene  or 
other  method.  The  answer  is  somewhat  difficult  if 
made  general.  There  are  no  doubt  some  cases  where 
the  use  of  a  drop  hammer  and  forge  fire  or  the  use  of 
the  oxy-acetylene  torch  will  make,  all  things  being 
considered,  a  better  job  than  the  use  of  the  electric 


lt>6  WELDING 

arc,  although  a  case  where  this  is  absolutely  proved  is 
rare. 

The  electric  arc  will  melt  metal  in  a  weld  for  less 
than  the  same  metal  can  be  melted  by  the  use  of  the 
oxy-acetylene  torch,  and,  on  account  of  the  fact  that 
the  heat  can  be  applied  exactly  where  it  is  required 
and  in  the  amount  required,  the  arc  can  in  almost  all 
cases  supply  welding  heat  for  less  cost  than  a  forge 
fire  or  heating  furnace. 

The  one  great  advantage  of  the  oxy-acetylene 
method  in  comparison  with  other  methods  of  welding 
is  the  fact  that  in  some  cases  of  very  thin  sheet,  the 
weld  can  be  made  somewhat  sooner  than  is  possible 
otherwise.  With  metal  of  18  gauge  or  thicker,  this 
advantage  is  eliminated.  In  cutting  steel,  the  oxy- 
acetylene  torch  is  superior  to  almost  any  other  pos- 
sible method. 

Arc  Welding  Machines. — A  consideration  of  the 
function  and  purpose  of  the  various  types  of  arc  weld- 
ing machines  shows  that  the  only  reason  for  the  use 
of  any  machine  is  either  for  conversion  of  the  cur- 
rent from  alternating  to  direct,  or,  if  the  current  is 
already  direct,  then  the  saving  in  the  application  of 
this  current  in  the  arc. 

It  is  practically  out  of  the  question  to  apply  an 
alternating  current  arc  to  welding  for  the  reason  that 
in  any  arc  practically  all  the  heat  is  liberated  at  the 
positive  electrode,  which  means  that,  in  alternating 
current,  half  the  heat  is  liberated  at  each  electrode 
as  the  current  changes  its  direction  of  flow  or  alter- 
nates. Another  disadvantage  of  the  alternating  arc  is 
that  it  is  difficult  of  control  and  application. 

In  all  arc  welding  by  the  use  of  the  carbon  arc, 
the  positive  electrode  is  made  the  piece  to  be  welded, 


ELECTRIC  WELDING  167 

while  in  welding  with  metallic  electrodes  this  may 
be  either  the  piece  to  be  welded  of  the  rod  that  is 
used  as  a  filler.  The  voltage  across  the  arc  is  a  vari- 
able quantity,  depending  on  the  length  of  the  flame, 
its  temperature  and  the  gases  liberated  in  the  arc. 
With  a  carbon  electrode  the  voltage  will  vary  from 
zero  to  forty-five  volts.  With  the  metallic  electrode 
the  voltage  will  vary  from  zero  to  thirty  volts.  It  is, 
therefore,  necessary  for  the  welding  machine  to  be 
able  to  furnish  to  the  arc  the  requisite  amount  of  cur- 
rent, this  amount  being  varied,  and  furnish  it  at  all 
times  at  the  voltage  required. 

The  simplest  welding  apparatus  is  a  resistance  in 
series  with  the  arc.  This  is  entirely  satisfactory  in 
every  way  except  in  cost  of  current.  By  the  use  of 
resistance  in  series  with  the  arc  and  using  220  volts 
as  the  supply,  from  eighty  to  ninety  per  cent  of  the 
current  is  lost  in  heat  at  the  resistance.  Another 
disadvantage  is  the  fact  that  most  materials  change 
their  resistance  as  their  temperature  changes,  thus 
making  the  amount  of  current  for  the  arc  a  variable 
quantity,  depending  on  the  temperature  of  the  resist- 
ance. 

There  have  been  various  methods  originated  for 
saving  the  power  mentioned  and  a  good  many  ma- 
chines have  been  put  on  the  market  for  this  pur- 
pose. All  of  them  save  some  power  over  what  a  plain 
resistance  would  use.  Practically  all  arc  welding  ma- 
chines at  the  present  time  are  motor  generator  sets, 
the  motor  of  which  is  arranged  for  the  supply  volt- 
age and  current,  this  motor  being  direct  connected  to 
a  compound  wound  generator  delivering  approxi- 
mately seventy-five  volts  direct  current.  Then  by  the 
use  of  a  resistance,  this  seventy-five  volt  supply  is 


168  WELDING 

applied  to  the  arc.  Since  the  voltage  across  the  arc 
will  vary  from  zero  to  fifty  volts,  this  machine  will 
save  from  zero  up  to  seventy  per  cent  of  the  power 
that  the  machine  delivers.  The  rest  of  the  power,  of 
course,  has  to  be  dissipated  in  the  resistance  used  in 
series  with  the  arc. 

A  motor  generator  set  which  can  be  purchased  from 
any  electrical  company,  with  a  long  piece  of  fence  wire 
wound  around  a  piece  of  asbestos,  gives  results  equally 
as  good  and  at  a  very  small  part  of  the  first  cost. 

It  is  possible  to  construct  a  machine  which  will 
eliminate  all  losses  in  the  resistance;  in  other  words, 
eliminate  all  resistance  in  series  with  the  arc.  A 
machine  of  this  kind  will  save  its  cost  within  a  very 
short  time,  providing  the  welder  is  used  to  any  extent. 

Putting  it  in  figures,  the  results  are  as  follows  for 
average  conditions.  Current  at  2c  per  kilowatt  hour, 
metallic  electrode  arc  of  150  amperes,  carbon  arc  500 
amperes ;  voltage  across  the  metallic  electrode  arc  20, 
voltage  across  the  carbon  arc  35.  Supply  current  220 
volts,  direct.  In  the  case  of  the  metallic  electrode,  if 
resistance  is  used,  the  cost  of  running  this  arc  is  sixty- 
six  cents  per  hour.  With  the  carbon  electrode,  $2.20 
per  hour.  If  a  motor  generator  set  with  a  seventy 
volt  constant  potential  machine  is  used  for  a  welder, 
the  cost  will  be  as  follows: 

Metallic  electrode  25.2c.  Carbon  electrode  84c  per 
hour.  With  a  machine  which  will  deliver  the  required 
voltage  at  the  arc  and  eliminate  all  the  resistance  in 
series  with  the  arc,  the  cost  will  be  as  follows :  Me- 
tallic electrode  7.2c  per  hour;  carbon  electrode  42c 
per  hour.  This  is  with  the  understanding  that  the 
arc  is  held  constant  and  continuously  at  its  full  value. 
This,  however,  is  practically  impossible  and  the  actual 


ELECTRIC  WELDING 


load  factor  is  approximately  fifty  per  cent,  wiiich 
would  mean  that  operating  a  welder  as  it  is  usually 
operated,  this  result  will  be  reduced  to  one-half  of 
that  stated  in  all  cases. 


CHAPTER  VII 
HAND  FOEGING  AND  WELDING 

Smithing,  or  blacksmithing,  is  the  process  of  work- 
ing heated  iron,  steel  or  other  metals  by  forging,  bend- 
ing or  welding  them. 

The  Forge. — The  metal  is  heated  in  a  forge  con- 
sisting of  a  shallow  pan  for  holding  the  fire,  in  the 
center  of  which  is  an  opening  from  below  through 
which  air  is  forced  to  make  a  hot  fire. 


Figure  48. — Tuyere  Construction  on  a  Forge 

Air  is  forced  through  this  hole,  called  a  "  tuyere " 
(Figure  48)  by  means  of  a  hand  bellows,  a  rotary 
fan  operated  with  crank  or  lever,  or  with  a  fan  driven 
from  an  electric  motor.  The  harder  the  air  is  driven 
into  the  fire  above  the  tuyere  the  more  oxygen  is  fur- 
nished and  the  hotter  the  fire  becomes. 

Directly  below  the  tuyere  is  an  opening  through 
which  the  ashes  that  drop  from  the  fire  may  be  cleaned 
out. 

170 


HAND  FORGING  AND  WELDING  171 

The  Fire. — The  fire  is  made  by  placing  a  small 
piece  of  waste  soaked  in  oil,  kerosene  or  gasoline,  over 
the  tuyere,  lighting  the  waste,  then  starting  the  fan 
or  blower  slowly.  Gradually  cover  the  waste,  while 
it  is  burning  brightly,  with  a  layer  of  soft  coal.  The 
coal  will  catch  fire  and  burn  after  the  waste  has  been 
consumed.  A  piece  of  waste  half  the  size  of  a  per- 
son's hand  is  ample  for  this  purpose. 

The  fuel  should  be  "smithing  coal."  A  lump  of 
smithing  coal  breaks  easily,  shows  clean  and  even  on 
all  sides  and  should  not  break  into  layers.  The  coal 
is  broken  into  fine  pieces  and  wet  before  being  used 
on  the  fire. 

The  fire  should  be  kept  deep  enough  so  that  there  is 
always  three  or  four  inches  of  fire  below  the  piece  of 
metal  to  be  heated  and  there  should  be  enough  fire 
above  the  work  so  that  no  part  of  the  metal  being 
heated  comes  in  contact  with  the  air.  The  fire  should 
be  kept  as  small  as  possible  while  following  these  rules 
as  to  depth. 

To  make  the  fire  larger,  loosen  the  coal  around  the 
edges.  To  make  the  fire  smaller,  pack  wet  coal  around 
the  edges  in  a  compact  mass  and  loosen  the  fire  in 
the  center.  Add  fresh  coal  only  around  the  edges  of 
the  fire.  It  will  turn  to  coke  and  can  then  be  raked 
onto  the  fire.  Blow  only  enough  air  into  the  fire  to 
keep  it  burning  brightly,  not  so  much  that  the  fire  is 
blown  up  through  the  top  of  the  coal  pack.  To  pre- 
vent the  fire  from  going  out  between  jobs,  stick  a  piece 
of  soft  wood  into  it  and  cover  with  fresh  wet  coal. 

Tools. — The  hammer  is  a  ball  pene,  or  blacksmith 's 
hammer,  weighing  about  a  pound  and  a  half. 

The  sledge  is  a  heavy  hammer,  weighing  from  5  to 
20  pounds  and  having  a  handle  30  to  36  inches  long. 


172 


WELDING 


The  anvil  is  a  heavy  piece  of  wronght  iron  (Figure 
49),  faced  with  steel  and  having  four  legs.  It  has  a 
pointed  horn  on  one  end,  an  overhanging  tail  on  the 
other  end  and  a  flat  top.  In  the  tail  there  is  a  square 
hole  called  the  " bardie"  hole  and  a  round  one  called 
the  "spud"  hole. 

Tongs,  with  handles  about  one  foot  long  and  jaws 
suitable  for  holding  the  work,  are  used.  To  secure  a 
firm  grip  on  the  work,  the  jaws  may  be  heated  red 


Figure  49. — Anvil,  Showing  Horn,  Tail,  Hardie  Hole  and  Spud  Hole 

hot  and  hammered  into  shape  over  the  piece  to  be 
held,  thus  giving  a  properly  formed  jaw.  Jaws  should 
touch  the  work  along  their  entire  length. 

The  set  hammer  is  a  hammer,  one  end  of  whose  head 
is  square  and  flat,  and  from  this  face  the  head  tapers 
evenly  to  the  other  face.  The  large  face  is  about  l!/4 
inches  square. 

The  flatter  is  a  hammer  having  one  face  of  its  head 
flat  and  about  2~y2  inches  square. 

Swages  are  hammers  having  specially  formed  faces 
for  finishing  rounds,  squares,  hexagons,  ovals,  tapers, 
etc. 


HAND  FORGING  AND  WELDING  173 

Fullers  are  hammers  having  a  rounded  face,  long 
in  one  direction.  They  are  used  for  spreading  metal 
in  one  direction  only. 

The  hardy  is  a  form  of  chisel  with  a  short,  square 
shank  which  may  be  set  into  the  hardie  hole  for  cut- 
ting off  hot  bars. 

Operations. — Blacksmithing  consists  of  bending, 
drawing  or  upsetting  with  the  various  hammers,  or 
in  punching  holes. 

Bending  is  done  over  the  square  corners  of  the 
anvil  if  square  cornered  bends  are  desired,  or  over  the 
horn  of  the  anvil  if  rounding  bends,  eyes,  hooks,  etc., 
are  wanted. 

To  bend  a  ring  or  eye  in  the  end  of  a  bar,  first  figure 
the  length  of  stock  needed  by  multiplying  the  diam- 
eter of  the  hole  by  31/7,  then  heat  the  piece  to  a 
good  full  red  at  a  point  this  distance  back  from  the 
end.  Next  bend  the  iron  over  at  a  90  degree  angle 
(square)  at  this  point.  Next,  heat  the  iron  from 
the  bend  just  made  clear  to  the  point  and  make  the 
eye  by  laying  the  part  that  was  bent  square  over  the 
horn  of  the  anvil  and  bending  the  extreme  tip  into 
part  of  a  circle.  Keep  pushing  the  piece  farther  and 
farther  over  the  horn  of  the  anvil,  bending  it  as  you 
go.  Do  not  hammer  directly  over  the  horn  of  the 
anvil,  but  on  the  side  where  you  are  doing  the 
bending. 

To  make  the  outside  of  a  bend  square,  sharp  and 
full,  rather  than  slightly  rounding,  the  bent  piece 
must  be  laid  edgewise  on  the  face  of  the  anvil.  That 
is,  after  making  the  bend  over  the  corner  of  the  anvil, 
lay  the  piece  on  top  of  the  anvil  so  that  its  edge  and 
not  the  flat  side  rests  on  the  anvil  top.  With  the  work 
in  this  position,  strike  directly  against  the  corner 


174  WELDING 

with  the  hammer  so  that  the  blows  come  in  line,  first 
with  one  leg  of  the  work,  then  the  other,  and  always 
directly  on  the  corner  of  the  piece.  This  operation 
cannot  be  performed  by  laying  the  w^ork  so  that  one 
leg  hangs  over  the  anvil's  corner. 

To  make  a  shoulder  on  a  rod  or  bar,  heat  the  work 
and  lay  flat  across  the  top  of  the  anvil  with  the  point 
at  which  the  shoulder  is  desired  at  the  edge  of  the 
anvil.  Then  place  the  set  hammer  on  top  of  the  piece, 
with  the  outside  edge  of  the  set  hammer  directly  over 
the  edge  of  the  anvil.  While  hammering  in  this  posi- 
tion keep  the  work  turning  continually. 

To  draw  stock  means  to  make  it  longer  and  thinner 
by  hammering.  A  piece  to  be  drawn  out  is  usually 
laid  across  the  horn  of  the  anvil  while  being  struck 
with  the  hammer.  The  metal  is  then  spread  in  only 
one  direction  in  place  of  being  spread  in  every  direc- 
tion, as  it  would  be  if  laid  on  the  anvil  face.  To 
draw  the  work,  heat  it  to  as  high  a  temperature  as  it 
will  stand  without  throwing  sparks  and  burning.  The 
fuller  may  be  used  for  drawing  metal  in  place  of  lay- 
ing the  work  over  the  horn  of  the  anvil. 

When  drawing  round  stock,  it  should  be  first  drawn 
out  square,  and  when  almost  down  to  size  it  may  be 
rounded.  When  pointing  stock,  the  same  rule  of  first 
drawing  out  square  applies. 

Upsetting  means  to  make  a  piece  shorter  in  length 
and  greater  in  thickness  or  width,  or  both  shorter  and 
thicker.  To  upset  short  pieces,  heat  to  a  bright  red  at 
the  place  to  be  upset,  then  stand  on  end  on  the  anvil 
face  and  hammer  directly  down  on  top  until  of  the 
right  form.  Longer  pieces  may  be  swung  against  the 
anvil  or  placed  upright  on  a  heavy  piece  of  metal 
lying  on  the  floor  or  that  is  sunk  into  the  floor.  While 


HAND  FORGING  AND  WELDING  175 

standing  on  this  heavy  piece  the  metal  may  be  upset 
by  striking  down  on  the  end  with  a  heavy  hammer  or 
the  sledge.  If  a  bend  appears  while  upsetting,  it 
should  be  straightened  by  hammering  back  into  shape 
on  the  anvil  face. 

Light  blows  affect  the  metal  for  only  a  short  dis- 
tance from  the  point  of  striking,  but  heavy  blows  tend 
to  swell  the  metal  more  equally  through  its  entire 
length.  In  driving  rivets  that  should  fill  the  holes, 
heavy  blows  should  be  struck,  but  to  shape  the  end  of 
a  rivet  or  to  make  a  head  on  a  rod,  light  blows  should 
be  used. 

The  part  of  the  piece  that  is  heated  most  will  upset 
the  most. 

To  punch  a  hole  through  metal,  use  a  tool  steel 
punch  with  its  end  slightly  tapering  to  a  size  a  little 
smaller  than  the  hole  to  be  punched.  The  end  of 
the  punch  must  be  square  across  and  never  pointed  or 
rounded. 

First  drive  the  punch  part  way.  through  from  one 
side  and  then  turn  the  work  over.  When  you  turn 
it  over,  notice  where  the  bulge  appears  and  in  that 
way  locate  the  hole  and  drive  the  punch  through  from 
the  second  side.  This  makes  a  cleaner  and  more  even 
hole  than  to  drive  completely  through  from  one  side. 
When  the  punch  is  driven ,  in  from  the  second  side, 
the  place  to  be  punched  through  •  should  be  laid  over 
the  spud  hole  in  the  tail  of  the  anvil  and  the  piece 
driven  out  of  the  work. 

Work  when  hot  is  larger  than  it  will  be  after  cool- 
ing. This  must  be  remembered  when  fitting  parts  or 
trouble  will  result.  A  two-foot  bar  of  steel  will  be 
!/4  inch  longer  when  red  hot  than  when  cold. 


176  WELDING 

The  temperatures  of  iron  correspond  to  the  fol- 
lowing colors : 

Dullest  red  seen  in  the  dark 878° 

Dullest  red  seen  in  daylight 887° 

Dull   red 1100° 

Full   red 1370° 

Light  red  1550° 

Orange    1650° 

Light  orange   1725° 

Yellow 1825° 

Light  yellow 1950° 

Bending  Pipes  and  Tubes. — It  is  difficult  to  make 
bends  or  curves  in  pipes  and  tubing  without  leaving 
a  noticeable  bulge  at  some  point  of  the  work.  Seam- 
less steel  tubing  may  be  handled  without  very  great 
danger  of  this  trouble  if  care  is  used,  but  iron  pipe, 
having  a  seam  running  lengthwise,  must  be  given 
special  attention  to  avoid  opening  the  seam. 

Bends  may  be  made  without  kinking  if  the  tube  or 
pipe  is  brought  to  a  full  red  heat  all  the  way  around 
its  circumference  and  at  the  place  where  the  bend 
is  desired.  Hold  the  cool  portion  solidly  in  a  vise 
and,  by  taking  hold  of  the  free  end,  bend  very  slowly 
and  with  a  steady  pull.  The  pipe  must  be  kept  at 
full  red  heat  with  the  flames  from  one  or  more  torches 
and  must  not  be  hammered  to  produce  the  bend. 
If  a  sufficient  purchase  cannot  be  secured  on  the  free 
end  by  the  hand,  insert  a  piece  of  rod  or  a  smaller 
pipe  into  the  opening. 

While  making  the  bend,  should  small  bulges  appear, 
they  may  be  hammered  back  into  shape  before  pro- 
ceeding with  the  work. 


HAND  FORGING  AND  WELDING  177 

Tubing  or  pipes  may  be  bent  while  being  held 
between  two  flat  metal  surfaces  while  at  a  bright 
red  heat.  The  metal  plates  at  each  side  of  the  work 
prevent  bulging. 

Another  method  by  which  tubing  may  be  bent 
consists  of  filling  completely  with  tightly  packed  sand 
and  fitting  a  solid  cap  or  plug  at  each  end. 

Thin  brass  tubing  may  be  filled  with  melted  resin 
and  may  be  bent  after  the  resin  cools.  To  remove 
the,  resin  it  is  necessary  to  heat  the  tube,  allowing 
it  to  run  out. 

Large  jobs  of  bending  should  be  handled  in  special 
pipe  bending  machines  in  which  the  work  is  forced 
through  formed  rolls  which  prevent  its  bulging. 

WELDING 

Welding  with  the  heat  of  a  blacksmith  forge  fire, 
or  a  coal  or  illuminating  gas  fire,  can  only  be  per- 
formed with  iron  and  steel  because  of  the  low  heat 
which  is  not  localized  as  with  the  oxy-acetylene  and 
electric  processes.  Iron  to  be  welded  "in  this  manner 
is  heated  until  it  reaches  the  temperature  indicated 
by  an  orange  color,  not  white,  as  is  often  stated,  this 
orange  color  being  slightly  above  1600  degrees  Fah- 
renheit. Steel  is  usually  welded  at  a  bright  red  heat 
because  of  the  danger  of  oxidizing  or  burning  the 
metal  if  the  temperature  is  carried  above  this  point. 

The  Fire. — If  made  in  a  forge,  the  fire  should  be 
built  from  good  smithing  coal  or,  better  still,  from 
coke.  Gas  fires  are,  of  course,  produced  by  suitable 
burners  and  require  no  special  preparation  except 
adjustment  of  the  heat  to  the  proper  degree  for  the 
size  and  thickness  of  the  metal  being  welded  so  that 
it  will  not  be  burned. 


178  WELDING 

A  coal  fire  used  for  ordinary  forging  operations 
should  not  be  used  for  welding  because  of  the  im- 
purities it  contains.  A  fresh  fire  should  be  built 
with  a  rather  deep  bed  of  coal,  four  to  eight  inches 
being  about  right  for  work  ordinarily  met  with.  The 
fire  should  be  kept  burning  until  the  coal  around  the 
edges  has  been  thoroughly  coked  and  a  sufficient 
quantity  of  fuel  should  be  on  and  around  the  fire 
so  that  no  fresh  coal  will  have  to  be  added  while 
working. 

After  the  coking  process  has  progressed  sufficiently, 
the  edges  should  be  packed  down  and  the  fire  made 
as  small  as  possible  while  still  surrounding  the  ends 
to  be  joined.  The  fire  should  not  be  altered  by  poking 
it  while  the  metal  is  being  heated.  The  best  form 
of  fire  to  use  is  one  having  rather  high  banks  of 
coked  coal  on  each  side  of  the  mass,  leaving  an  open- 
ing or  channel  from  end  to  end.  This  will  allow  the 
added  fuel  to  be  brought  down  on  top  of  the  fire 
with  a  small  amount  of  disturbance. 

Preparing  to  Weld. — If  the  operator  is  not  familiar 
with  the  metal  to  be  handled,  it  is  best  to  secure  a 
test  piece  if  at  all  possible  and  try  heating  it  and 
joining  the  ends.  Various  grades  of  iron  and  steel 
call  for  different  methods  of  handling  and  for  dif- 
ferent degrees  of  heat,  the  proper  method  and  tem- 
perature being  determined  best  by  actual  test  under 
the  hammer. 

The  form  of  the  pieces  also  has  a  great  deal  to  do 
with  their  handling,  especially  in  the  case  of  a  more 
or  less  inexperienced  workman.  If  the  pieces  are 
at  all  irregular  in  shape,  the  motions  should  be  gone 
through  with  before  the  metal  is  heated  and  the  best 
positions  on  the  anvil  as  well  as  in  the  fire  deter- 


HAND  FORGING  AND  WELDING  179 

mined  with  regard  to  the  convenience  of  the  workman 
and  speed  of  handling  the  work  after  being  brought 
to  a  welding  temperature.  Unnatural  positions  at 
the  anvil  should  be  avoided  as  good  work  is  most 
difficult  of  performance  under  these  conditions. 

Scarfing. — While  there  are  many  forms  of  welds, 
depending  on  the  relative  shape  of  the  pieces  to  be 
joined,  the  portions  that  are  to  meet  and  form  one 
piece  are  always  shaped  in  the  same  general  way, 
this  shape  being  called  a  ' '  scarf. "  The  end  of  a 
piece  of  work,  when  scarfed,  is  tapered  off  on  one 
side  so  that  the  extremity  comes  to  a  rather  sharp 
edge.  The  other  side  of  the  piece  is  left  flat  and  a 


Figure  50. — Scarfing  Ends  of  Work  Ready  for  Welding 

continuation  in  the  same  straight  plane  with  its  side 
of  the  whole  piece  of  work.  The  end  is  then  in  the 
form  of  a  bevel  or  mitre  joint  (Figure  50). 

Scarfing  may  be  produced  in  any  one  of  several 
ways.  The  usual  method  is  to  bring  the  ends  to  a 
forging  heat,  at  which  time  they  are  upset  to  give 
a  larger  body  of  metal  at  the  ends  to  be  joined.  This 
body  of  metal  is  then  hammered  down  to  the  taper 
on  one  side,  the  length  of  the  tapered  portion  being 
about  one  and  a  half  times  the  thickness  of  the  whole 
piece  being  handled.  Each  piece  should  be  given 
this  shape  before  proceeding  farther. 

The  scarf  may  be  produced  by  filing,  sawing  or 
chiseling  the  ends,  although  this  is  not  good  practice 
because  it  is  then  impossible  to  give  the  desired  upset 
and  additional  metal  for  the  weld.  This  added  thick- 


180  WELDING 

ness  is  called  for  by  the  fact  that  the  metal  burns 
away  to  a  certain  extent  or  turns  to  scale,  which  is 
removed  before  welding. 

When  the  two  ends  have  been  given  this  shape 
they  should  not  fit  as  closely  together  as  might  be 
expected,  but  should  touch  only  at  the  center  of  the 
area  to  be  joined  (Figure  51).  That  is  to  say,  the 
surface  of  the  beveled  portion  should  bulge  in  the 
middle  or  should  be  convex  in  shape  so  that  the  edges 
are  separated  by  a  little  distance  when  the  pieces  are 
laid  together  with  the  bevels  toward  each  othefr. 
This  is  done  so  that  the  scale  which  is  formed  on  the 


Figure  51. — Proper  Shape  of  Scarfed  Ends 

metal  by  the  heat  of  the  fire  can  have  a  chance  to 
escape  from  the  interior  of  the  weld  as  the  two  parts 
are  forced  together. 

If  the  scarf  were  to  be  formed  with  one  or  more 
of  the  edges  touching  each  other  at  the  same  time 
or  before  the  centers  did  so,  the  scale  would  be  im- 
prisoned within  the  body  of  the  weld  and  would  cause 
the  finished  work  to  be  weak,  while  possibly  giving 
a  satisfactory  appearance  from  the  outside. 

Fluxes. — In  order  to  assist  in  removing  the  scale 
and  other  impurities  and  to  make  the  welding  sur- 
faces as  clean  as  possible  while  being  joined,  various 
fluxing  materials  are  used  as  in  other  methods  of 
welding. 

For  welding  iron,  a  flux  of  white  sand  is  usually 
used,  this  material  being  placed  on  the  metal  after 
it  has  been  brought  to  a  red  heat  in  the  fire.  Steel 


HAND  FORGING  AND  WELDING  181 

is  welded  with  dry  borax  powder,  this  flux  being 
applied  at  the  same  time  as  the  iron  flux  just  men- 
tioned. Borax  may  also  be  used  for  iron  welding 
and  a  mixture  of  borax  with  steel  borings  may  also 
be  used  for  either  class  of  work.  Mixtures  of  sal 
ammoniac  with  borax  have  been  successfully  used, 
the  proportions  being  about  four  parts  of  borax  to 
one  of  sal  ammoniac.  Various  prepared  fluxing 
powders  are  on  the  market  for  this  work,  practically 
all  of  them  producing  satisfactory  results. 

After  the  metal  has  been  in  the  fire  long  enough 
to  reach  a  red  heat,  it  is  removed  temporarily  and, 
if  small  enough  -in  size,  the  ends  are  dipped  into  a 
box  of  flux.  If  the  pieces  are  large,  they  may  simply 
be  pulled  to  the  edge  of  the  fire  and  the  flux  then 
sprinkled  on  the  portions  to  be  joined.  A  greater 
quantity  of  flux  is  required  in  forge  welding  than 
in  electric  or  oxy-acetylene  processes  because  of  the 
losses  in  the  fire.  After  the  powder  has  been  applied 
to  the  surfaces,  the  work  is  returned  to  the  fire  and 
heated  to  the  welding  temperature. 

Heating  the  Work. — After  being  scarfed,  the  two 
pieces  to  be  welded  are  placed  in  the  fire  and  brought 
to  the  correct  temperature.  This  temperature  can 
only  be  recognized  by  experiment  and  experience. 
The  metal  must  be  just  below  that  pomt  at  which 
small  sparks  begin  to  be  thrown  out  of  the  fire  and 
naturally  this  is  a  hard  point  to  distinguish.  At  the 
welding  heat  the  metal  is  almost  ready  to  flow  and  is 
about  the  consistency  of  putty.  Against  the  back- 
ground of  the  fire  and  coal  the  color  appears  to  be 
a  cream  or  very  light  yellow  and  the  work  feels  soft 
as  it  is  handled. 

It  is  absolutely  necessary  that  both  parts  be  heated 


182  WELDING 

uniformly  and  so  that  they  reach  the  welding  tern-* 
perature  at  the  same  time.  For  this  reason  they 
should  be  as  close  together  in  the  fire  as  possible  and 
side  by  side.  When  removed  to  be  hammered  to- 
gether, time  is  saved  if  they  are  picked  up  in  such 
a  way  that  when  laid  together  naturally  the  beveled 
surfaces  come  together.  This  makes  it  necessary  that 
the  workman  remember  whether  the  scarfed  side  is 
up  or  down,  and  to  assist  in  this  it  is  a  good  thing 
to  mark  the  scarfed  side  with  chalk  or  in  some  other 
noticeable  manner,  so  that  no  mistake  will  be  made 
in  the  hurry  of  placing  the  work  on  the  anvil. 

The  common  practice  in  heating  allows  the  tem- 
perature to  rise  until  the  small  white  sparks  are  seen 
to  come  from  the  fire.  Any  heating  above  this  point 
will  surely  result  in  burning  that  will  ruin  the  iron 
or  steel  being  handled.  The  best  welding  heat  can 
be  discerned  by  the  appearance  of  the  metal  and 
its  color  after  experience  has  been  gained  with  this 
particular  material.  Test  welds  can  be  made  and 
then  broken,  if  possible,  so  that  the  strength  gained 
through  different  degrees  of  heat  can  be  known 
before  attempting  more  important  work. 

Welding. — When  the  work  has  reached  the  welding 
temperature  after  having  been  replaced  in  the  fire 
with  the  flux  applied,  the  two  parts  are  quickly 
tapped  to  remove  the  loose  scale  from  their  surfaces. 
They  are  then  immediately  laid  across  the  top  of  the 
anvil,  being  placed  in  a  diagonal  position  if  both 
pieces  are  straight.  The  lower  piece  is  rested  on  the 
anvil  first  with  the  scarf  turned  up  and  ready  to 
receive  the  top  piece  in  the  position  desired.  The 
second  piece  must  be  laid  in  exactly  the  position  it 
is  to  finally  occupy  because  the  two  parts  will  stick 


HAND  FORGING  AND  WELDING  183 

together  as  soon  as  they  touch  and  they  cannot  well 
be  moved  after  having  once  been  allowed  to  come  in 
contact  with  each  other.  This  part  of  the  work  must 
be  done  without  any  unnecessary  loss  of  time  because 
the  comparatively  low  heat  at  which  the  parts  weld 
allows  them  to  cool  below  the  working  temperature 
in  a  few  seconds. 

The  greatest  difficulty  will  be  experienced  in  with- 
drawing the  metal  from  the  fire  before  it  becomes 
burned  and  in  getting  it  joined  before  it  cools  below 
this  critical  point.  The  beveled  edges  of  the  scarf 
are,  of  course,  the  first  parts  to  cool  and  the  weld 
must  be  made  before  they  reach  a  point  at  which  they 
will  not  join,  or  else  the  work  will  be  defective  in 
appearance  and  in  fact. 

If  the  parts  being  handled  are  of  such  a  shape  that 
there  is  danger  of  bending  a  portion  back  of  the 
weld,  this  part  may  be  cooled  by  quickly  dipping  it 
into  water  before  laying  the  work  on  the  anvil  to 
be  joined.  , 

The  workman  uses  a  heavy  hand  hammer  in  making 
the  joint,  and  his  helper,  if  one  is  employed,  uses  a 
sledge.  With  the  two  parts  of  the  work  in  place 
on  the  anvil,  the  workman  strikes  several  light  blows, 
the  first  ones  being  at  a  point  directly  over  the  center 
of  the  weld,  so  that  the  joint  will  start  from  this 
point  and  be  worked  toward  the  edges.  After  the 
pieces  have  united  the  helper  strikes  alternate  blows 
with  his  sledge,  always  striking  in  exactly  the  same 
place  as  the  last  stroke  of  the  workman.  The  hammer 
blows  are  carried  nearer  and  nearer  to  the  edges  of 
the  weld  and  are  made  steadily  heavier  as  the  work 
progresses. 

The   aim   during  the   first  part   of  the   operation 


184  WELDING 

should  be  to  make  a  perfect  joint,  with  every  part 
of  the  surfaces  united,  and  too  much  attention  should 
not  be  paid  to  appearance,  at  least  not  enough  to 
take  any  chance  with  the  strength  of  the  work. 

It  will  be  found,  after  completion  of  the  weld,  that 
there  has  been  a  loss  in  length  equal  to  one-half  the 
thickness  of  the  metal  being  welded.  This  loss  is 
occasioned  by  the  burned  metal  and  the  scale  which 
has  been  formed. 

Finishing  the  Weld. — If  it  is  possible  to  do  so,  the 
material  should  be  hammered  into  the  shape  that  it 
should  remain  with  the  same  heat  that  was  used  for 


Figure  52. — Upsetting  and  Scarfing  the  End  of  a  Rod 

welding.  It  will  usually  be  found,  however,  that  the 
metal  has  cooled  below  the  point  at  which  it  can  be 
worked  to  advantage.  It  should  then  be  replaced  in 
the  fire  and  brought  back  to  a  forging  heat. 

While  shaping  the  work  at  this  forging  heat  every 
part  that  has  been  at  a  red  heat  should  be  ham- 
mered with  uniformly  light  and  even  blows  as  it  cools. 
This  restores  the  grain  and  strength  of  the  iron  or 
steel  to  a  great  extent  and  makes  the  unavoidable 
weakness  as  small  as  possible. 

Forms  of  Welds. — The  simplest  of  all  welds  is  that 
called  a  "lap  weld."  This  is  made  between  the  ends 
of  two  pieces  of  equal  size  and  similar  form  by 
scarfing  them  as  described  and  then  laying  one  on 
top  of  the  other  while  they  are  hammered  together. 

A  butt  weld  (Figure  52)  is  made  between  the  ends 


HAND  FORGING  AND  WELDING  185 

of  two  pieces  of  shaft  or  other  bar  shapes  by  upsetting 
the  ends  so  that  they  have  a  considerable'  flare  and 
shaping  the  face  of  the  end  so  that  it  is  slightly 
higher  in  the  center  than  around  the  edges,  this  being 
done  to  make  the  centers  come  together  first.  The 
pieces  are  heated  and  pushed  into  contact,  after  which 
the  hammering  is  done  as  with  any  other  weld. 

A  form  similar  to  the  butt  weld  in  some  ways  is 
used  for  joining  the  end  of  a  bar  to  a  flat  surface 
and  is  called  a  jump  weld.  The  bar  is  shaped  in 
the  same  way  as  for  a  butt  weld.  The  flat  plate 


Figure  53. — Scarfing  for  a  T  Weld 


may  be  left  as  it  is,  but  if  possible  a  depression 
should  be  made  at  the  point  where  the  shaft  is  to 
be  placed.  With  the  two  parts  heated  as  usual,  the 
bar  is  dropped  into  position  and  hammered  from 
above.  As  soon  as  the  center  of  the  weld  has  been 
made  perfect,  the  joint  may  be  finished  with  a  fuller 
driven  all  the  way  around  the  edge  of  the  joint. 

When  it  is  required  to  join  a  bar  to  another  bar 
or  to  the  edge  of  any  piece  at  right  angles  the  work 
is  called  a  "T"  weld  from  its  shape  when  complete 
(Figure  53).  The  end  of  the  bar  is  scarfed  as 
described  and  the  point  of  the  other  bar  or  piece 
where  the  weld  is  to  be  made  is  hammered  so  that  it 
tapers  to  a  thin  edge  like  one-half  of  a  circular 


186  WELDING 

depression.     The  pieces  are  then  laid  together  and 
hammered  as  for  a  lap  weld. 

The  ends  of  heavy  bar  shapes  are  often  joined 
with  a  "V,"  or  cleft,  weld.  One  bar  end  is  shaped 
so  that  it  is  tapering  on  both  sides  and  comes  to  a 
broad  edge  like  the  end  of  a  chisel.  The  other  bar 
is  heated  to  a  forging  temperature  and  then  slit  open 
in  a  lengthwise  direction  so  that  the  V-shaped  open- 
ing which  is  formed  will  just  receive  the  pointed  edge 
of  the  first  piece.  With  the  work  at  welding  heat, 
the  two  parts  are  driven  together  by  hammering  on 
the  rear  ends  and  the  hammering  then  continues  as 


7 


Figure  54. — Splitting  Ends  to  Be  Welded  in  Thin  Work 

with  a  lap  weld,  except  that  the  work  is  turned  over 
to  complete  both  sides  of  the  joint. 

The  forms  so  far  described  all  require  that  the 
pieces  be  laid  together  in  the  proper  position  after 
removal  from  the  fire,  and  this  always  causes  a  slight 
loss  of  time  and  a  consequent  lowering  of  the  tem- 
perature. With  very  light  stock,  this  fall  of  tem- 
perature would  be  so  rapid  that  the  weld  would  be 
unsuccessful,  and  in  this  case  the  "lock"  weld  is 
resorted  to.  The  ends  of  the  two  pieces  to  be  joined 
are  split  for  some  distance  back,  and  one-half  of  each 
end  is  bent  up  and  the  other  half  down  (Figure  54). 
The  two  are  then  pushed  together  and  placed  in  the 
fire  in  this  position.  When  the  welding  heat  is 
reached,  it  is  only  necessary  to  take  the  work  out  of 
the  fire  and  hammer  the  parts  together,  inasmuch  as 
they  are  already  in  the  correct  position. 


HAND  FORGING  AND  WELDING  187 

Other  forms  of  welds  in  which  the  parts  are  too 
small  to  retain  their  heat,  can  be  made  by  first 
riveting  them  together  or  cutting  them  so  that  they 
can  be  temporarily  fastened  in  any  convenient  way 
when  first  placed  in  the  fire. 


CHAPTER  VIII 

SOLDERING,  BRAZING  AND   THERMIT  WELDING 
SOLDERING 

Common  solder  is  an  alloy  of  one-half  lead  with 
one-half  tin,  and  is  called  "half  and  half."  Hard 
solder  is  made  with  two-thirds  tin  and  one-third  lead. 
These  alloys,  when  heated,  are  used  to  join  surfaces 
of  the  same  or  dissimilar  metals  such  as  copper,  brass, 
lead,  galvanized  iron,  zinc,  tinned  plate,  etc.  These 
metals  are  easily  joined,  but  the  action  of  solder  with 
iron,  steel  and  aluminum  is  not  so  satisfactory  and 
requires  greater  care  and  skill. 

The  solder  is  caused  to  make  a  perfect  union  with 
the  surfaces  treated  with  the  help  of  heat  from  a 
soldering  iron.  The  soldering  iron  is  made  from  a 
piece  of  copper,  pointed  at  one  end  and  with  the 
other  end  attached  to  an  iron  rod  and  wooden  handle. 
A  flux  is  used  to  remove  impurities  from  the  joint 
and  allow  the  solder  to  secure  a  firm  union  with  the 
metal  surface.  The  iron,  and  in  many  cases  the  work, 
is  heated  with  a  gasoline  blow  torch,  a  small  gas 
furnace,  an  electric  heater  or  an  acetylene  and  air 
torch. 

The  gasoline  torch  which  is  most  commonly  used 
should  be  filled  two-thirds  full  of  gasoline  through 
the  hole  in  the  bottom,  which  is  closed  by  a  screw 
plug.  After  working  the  small  hand  pump  for  10 
to  20  strokes,  hold  the  palm  of  your  hand  over  the 
end  of  the  large  iron  tube  on  top  of  the  torch  and 
open  the  gasoline  needle  valve  about  a  half  turn. 
Hold  the  torch  so  that  the  liquid  runs  down  into 

188 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        189 

the  cup  below  the  tube  and  fills  it.  Shut  the  gasoline 
needle  valve,  wipe  the  hands  dry,  and  set  fire  to 
the  fuel  in  the  cup.  Just  as  the  gasoline  fire  goes 
out,  open  the  gasoline  needle  valve  about  a  half  turn 
and  hold  a  lighted  match  at  the  end  of  the  iron  tube 
to  ignite  the  mixture  of  vaporized  gasoline  and  air. 
Open  or  close  the  needle  valve  to  secure  a  flame  about 
4  inches  long. 

On  top  of  the  iron  tube  from  which  the  flame  issues 
there  is  a  rest  for  supporting  the  soldering  iron  with 
the  copper  part  in  the  flame.  Place  the  iron  in  the 
flame  and  allow  it  to  remain  until  the  copper  becomes 
very  hot,  not  quite  red,  but  almost  so. 

A  new  soldering  iron  or  one  that  has  been  misused 
will  have  to  be  "  tinned "  before  using.  To  do  this, 
take  the  iron  from  the  fire  while  very  hot  and  rub 
the  tip  on  some  flux  or  dip  it  into  soldering  acid. 
Then  rub  the  tip  of  the  iron  on  a  stick  of  solder  or 
rub  the  solder  on  the  iron.  If  the  solder  melts  off  the 
stick  without  coating  the  end  of  the  iron,  allow  a 
few  drops  to  fall  on  a  piece  of  tin  plate,  then  rub 
the  end  of  the  iron  on  the  tin  plate  with  considerable 
force.  Alternately  rub  the  iron  on  the  solder  and 
dip  into  flux  until  the  tip  has  a  coating  of  bright 
solder  for  about  half  an  inch  from  the  end.  If  the 
iron  is  in  very  bad  shape,  it  may  be  necessary  to 
scrape  or  file  the  end  before  dipping  in  the  flux  for 
the  first  time.  After  the  end  of  the  iron  is  tinned 
in  this  way,  replace  it  on  the  rest  of  the  torch  so  that 
the  tinned  point  is  not  directly  in  the  flame,  turning 
the  flame  down  to  accomplish  this. 

Flux. — The  commonest  flux,  which  is  called  "sol- 
dering acid,"  is  made  by  placing  pieces  of  zinc  in 
muriatic  (hydrochloric)  acid  contained  in  a  heavy 


190  WELDING 

glass  or  porcelain  dish.  There  will  be  bubbles  and 
considerable  heat  evolved  and  zinc  should  be  added 
until  this  action  ceases  and  the  zinc  remains  in  the 
liquid,  which  is  now  chloride  of  zinc. 

This  soldering  acid  may  be  used  on  any  metal  to 
be  soldered  by  applying  with  a  brush  or  swab.  For 
electrical  work,  this  acid  should  be  made  neutral  by 
the  addition  of  one  part  ammonia  and  one  part  water 
to  each  three  parts  of  the  acid.  This  neutralized  flux 
will  not  corrode  metal  as  will  the  ordinary  acid. 

Powdered  resin  makes  a  good  flux  for  lead,  tin 
plate,  galvanized  iron  and  aluminum.  Tallow,  olive 
oil,  beeswax  and  vaseline  are  also  used  for  this  pur- 
pose. Muriatic  acid  may  be  used  for  zinc  or  gal- 
vanized iron  without  the  addition  of  the  zinc,  as  de- 
scribed in  making  zinc  chloride.  The  addition  of 
two  heaping  teaspoonfuls  of  sal  ammoniac  to  each 
pint  of  the  chloride  of  zinc  is  sometimes  found  to- 
improve  its  action. 

Soldering  Metal  Parts. — All  surfaces  to  be  joined 
should  be  fitted  to  each  other  as  accurately  as  pos- 
sible and  then  thoroughly  cleaned  with  a  file,  emery 
cloth,  scratch  bush  or  by  dipping  in  lye.  "Work  may 
be  cleaned  by  dipping  it  into  nitric  acid  which  has 
been  diluted  with  an  equal  volume  of  water.  The 
work  should  be  heated  as  hot  as  possible  without 
danger  of  melting,  as  this  causes  the  solder  to  flow 
better  and  secure  a  much  better  hold  on  the  surfaces. 
Hard  solder  gives  better  results  than  half  and  half, 
but  is  more  difficult  to  work.  It  is  very  important 
that  the  soldering  iron  be  kept  at  a  high  heat  during 
all  work,  otherwise  the  solder  will  only  stick  to  the 
surfaces  and  will  not  join  with  them. 

Sweating  is  a  form  of  soldering  in  which  the  sur- 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        191 

faces  of  the  work  are  first  covered  with  a  thin  layer 
of  solder  by  rubbing  them  with  the  hot  iron  after 
it  has  been  dipped  in  or  touched  to  the  soldering 
stick.  These  surfaces  are  then  placed  in  contact 
and  heated  to'  a  point  at  which  the  solder  melts  and 
unites.  Sweating  is  much  to  be  preferred  to  ordinary 
soldering  where  the  form  of  the  work  permits  it. 
This  is  the  only  method  which  should  ever  be  used 
when  a  fitting  is  to  be  placed  over  the  end  of  a  length 
of  tube. 

Soldering  Holes. — Clean  the  surfaces  for  some  dis- 
tance around  the  hole  until  they  are  bright,  and  apply 
flux  while  holding  the  hot  iron  near  the  hole.  Touch 
the  tip  of  the  iron  to  some  solder  until  the  solder  is 
picked  up  on  the  iron,  and  then  place  this  solder, 
which  was  just  picked  up,  around  the  edge  of  the 
hole.  It  will  leave  the  soldering  iron  and  stick  to 
the  metal.  Keep  adding  solder  in  this  way  until  the 
hole  has  been  closed  up  by  working  from  the  edges 
and  building  toward  the  center.  After  the  hole  is 
closed,  apply  more  flux  to  the  job  and  smooth  over 
with  the  hot  iron  until  there  are  no  rough  spots. 
Should  the  solder  refuse  to  flow  smoothly,  the  iron 
is  not  hot  enough. 

Soldering  Seams. — Clean  back  from  the  seam  or 
split  for  at  least  half  an  inch  all  around  and  then 
build  up  the  solder  in  the  same  way  as  was  done  writh 
the  hole.  After  closing  the  opening,  apply  more  flux 
to  the  work  and  run  the  hot  iron  lengthwise  to 
smooth  the  job. 

Soldering  Wires. — Clean  all  insulation  from  the 
ends  to  be  soldered  and  scrape  the  ends  bright.  Lay 
the  ends  parallel  to  each  other  and,  starting  at  the 
middle  of  the  cleaned  portion,  wrap  the  ends  around 


192 

each  other,  one  being  wrapped  to  the  right,  the  other 
to  the  left.  Hold  the  hot  iron  under  the  twisted  joint 
and  apply  flux  to  the  wire.  Then  dip  the  iron  in 
the  solder  and  apply  to  the  twisted  portion  until 
the  spaces  between  the  wires  are  filled  with  solder. 
Finish  by  smoothing*  the  joint  and  cleaning  away 
all  excess  metal  by  rubbing  the  hot  iron  lengthwise. 
The  joint  should  now  be  covered  with  a  layer  of 
rubber  tape  and  this  covered  with  a  layer  of  ordinary 
friction  tape. 

Steel  and  Iron. — Steel  surfaces  should  be  cleaned, 
then  covered  with  clear  muriatic  acid.  "While  the 
acid  is  on  the  metal,  rub  with  a  stick  of  zinc  and  then 
tin  the  surfaces  with  the  hot  iron  as  directed.  Cast 
iron  should  be  cleaned  and  dipped  in  strong  lye  to 
remove  grease.  Wash  the  lye  away  with  clean  water 
and  cover  with  muriatic  acid  as  with  steel.  Then 
rub  with  a  piece  of  zinc  and  tin  the  surfaces  by 
using  resin  as  a  flux. 

It  is  very  difficult  to  solder  aluminum  with  ordi- 
nary solder.  A  special  aluminum  solder  should  be 
secured,  which  is  easily  applied  and  makes  a  strong 
joint.  Zinc  or  phosphor  tin  may  be  used  in  place 
of  ordinary  solder  to  tin  the  surfaces  or  to  fill  small 
holes  or  cracks.  The  aluminum  must  be  thoroughly 
heated  before  attempting  to  solder  and  the  flux  may 
be  either  resin  or  soldering  acid.  The  aluminum  must 
be  thoroughly  cleaned  with  dilute  nitric  acid  and 
kept  hot  while  the  solder  is  applied  by  forcible  rub- 
bing with  the  hot  iron. 

BRAZING 

This  is  a  process  for  joining  metal  parts,  very 
similar  to  soldering,  except  that  brass  is  used  to 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        193 

make  the  joint  in  place  of  the  lead  and  zinc  alloys 
which  form  solder.  Brazing  must  not  be  attempted 
on  metals  whose  melting  point  is  less  than  that  of 
sheet  brass. 

Two  pieces  of  brass  to  be  brazed  together  are  heated 
to  a  temperature  at  which  the  brass  used  in  the  process 
will  melt  and  flow  between  the  surfaces.  The  brass 
amalgamates  with  the  surfaces  and  makes  a  very 
strong  and  perfect  joint,  which  is  far  superior  to 
any  form  of  soldering  where  the  work  allows  this 
process  to  be  used,  and  in  many  cases  is  the  equal  of 
welding  for  the  particular  field  in  which  it  applies. 

Brazing  Heat  and  Tools. — The  metal  commonly 
used  for  brazing  will  melt  at  heats  between  1350° 
and  1650°  Fahrenheit.  To  bring  the  parts  to  this 
temperature,  various  methods  are  in  use,  using  solid, 
liquid  or  gaseous  fuels.  While  brazing  may  be  ac- 
complished with  the  fire  of  the  blacksmith  forge,  this 
method  is  seldom  satisfactory  because  of  the  difficulty 
of  making  a  sufficiently  clean  fire  with  smithing  coal, 
and  it  should  not  be  used  when  anything  else  is 
available.  Large  jobs  of  brazing  may  be  handled 
with  a  charcoal  fire  built  in  the  forge,  as  this  fuel 
produces  a  very  satisfactory  and  clean  fire.  The 
only  objection  is  in  the  difficulty  of  confining  the 
heat  to  the  desired  parts  of  the  work. 

The  most  satisfactory  fire  is  that  from  a  fuel  gas 
torch  built  for  this  work.  These  torches  are  simply 
forms  of  Bunsen  burners,  mixing  the  proper  quan- 
tity of  air  with  the  gas  to  bring  about  a  perfect 
combustion.  Hose  lines  lead  to  the  mixing  tube  of 
the  gas  torch,  one  line  carrying  the  gas  and  the  other 
air  under  a  moderate  pressure.  The  air  line  is  often 
dispensed  with,  allowing  the  gas  to  draw  air  into  the 


194  WELDING 

burner  on  the  injector  principle,  much  the  same  as 
with  illuminating  gas  burners  for  use  with  incan- 
descent mantles.  Valves  are  provided  with  which 
the  operator  may  regulate  the  amount  of  both  gas 
and  air,  and  ordinarily  the  quality  and  intensity 
of  the  flame. 

When  gas  is  not  available,  recourse  may  be  had 
to  the  gasoline  torch  made  for  brazing.  This  torch 
is  built  in  the  same  way  as  the  small  portable  gasoline 
torches  for  soldering  operations,  with  the  exception 
that  two  regulating  needle  valves  are  incorporated 
in  place  of  only  one. 

The  torches  are  carried  on  a  framework,  which  also 
supports  the  work  being  handled.  Fuel  is  forced 
to  the  torch  from  a  large  tank  of  gasoline  into  which 
air  pressure  is  pumped  by  hand.  The  torches  are 
regulated  to  give  the  desired  flame  by  means  of  the 
needle  valves  in  much  the  same  way  as  with  any 
other  form  of  pressure  torch  using  liquid  fuel. 

Another  very  satisfactory  form  of  torch  for  brazing 
is  the  acetylene-air  combination  described  in  the 
chapter  on  welding  instruments.  This  torch  gives 
the  correct  degree  of  heat  and  may  be  regulated  to 
give  a  clean  and  easily  controlled  flame. 

Regardless  of  the  source  of  heat,  the  fire  or  flame 
must  be  adjusted  so  that  no  soot  is  deposited  on  the 
metal  surfaces  of  the  work.  This  can  only  be  accom- 
plished by  supplying  the  exact  amounts  of  gas  and 
air  that  will  produce  a  complete  burning  of  the  fuel. 
With  the  brazing  torches  in  common  use  two  heads 
are  furnished,  being  supplied  from  the  same  source 
of  fuel,  but  with  separate  regulating  devices,  The 
torches  are  adjustably  mounted  in  such  a  way  that 
the  flames  may  be  directed  toward  each  other,  heat- 


SOLDERING,  BRAZING  AND  THERMIT  WELDING         19£ 

ing  two  sides  of  the  work  at  the  same  time  and  allow- 
ing the  pieces  to  be  completely  surrounded  with  the 
flame. 

Except  for  the  source  of  heat,  tut  one  tool  is 
required  for  ordinary  brazing  operations,  this  being 
a  spatula  formed  by  flattening  one  end  of  a  quarter- 
inch  steel  rod.  The  spatula  is  used  for  placing  the 
brazing  metal  on  the  work  and  for  handling  the  flux 
that  is  required  in  this  work  as  in  all  other  similar 
operations. 

Spelter. — The  metal  that  is  melted  into  the  joint  is 
called  spelter.  While  this  name  originally  applied 
to  but  one  particular  grade  or  composition  of  metal, 
common  use  has  extended  the  meaning  until  it  is 
generally  applied  to  all  grades. 

Spelter  is  variously  composed  of  alloys  containing 
copper,  zinc,  tin  and  antimony,  the  mixture  employed 
depending  on  the  work  to  be  done.  The  different 
grades  are  of  varying  hardness,  the  harder  kinds 
melting  at  higher  temperatures  than  the  soft  ones 
and  producing  a  stronger  joint  when  used.  The 
reason  for  not  using  hard  spelter  in  all  cases  is  the 
increased  difficulty  of  working  it  and  the  fact  that 
its  melting  point  is  so  near  to  some  of  the  metals 
brazed  that  there  is  great  danger  of  melting  the  work 
as  well  as  the  spelter. 

The  hardest  grade  of  spelter  is  made  from  three- 
fourths  copper  with  one-fourth  zinc  and  is  used  for 
working  on  malleable  and  cast  iron  and  for  steel. 
This  hard  spelter  melts  at  about  1650°  and  is  cor- 
respondingly difficult  to  handle. 

A  spelter  suitable  for  working  with  copper  is  made 
from  equal  parts  of  copper  and  zinc,  melting  at  about 
1400°  Fahrenheit,  500°  below  the  melting  point  of 


196  WELDING 

the  copper  itself.  A  still  softer  brazing  metal  is 
composed  of  half  copper,  three-eighths  zinc  and  one- 
eighth  tin.  This  grade  is  used  for  fastening  brass  to 
iron  and  copper  and  for  working  with  large  pieces  of 
brass "  to  brass.  For  brazing  thin  sheet  brass  and 
light  brass  castings,  a  metal  is  used  which  contains 
two-thirds  tin  and  one-third  .antimony.  The  low 
melting  point  of  this  last  composition  makes  it  very 
easy  to  work  with  and  the  danger  of  melting  the 
work  is  very  slight.  However,  as  might  be  expected, 
a  comparatively  weak  joint  is  secured,  which  will  not 
stand  any  great  strain. 

All  of  the  above  brazing  metals  are  used  in  powrder 
form  so  that  they  may  be  applied  with  the  spatula 
where  the  joint  is  exposed  on  the  outside  of  the 
work.  In  case  it  is  necessary  to  braze  on  the  inside 
of  a  tube  or  any  deep  recess,  the  spelter  may  be 
placed  on  a  flat  rod  long  enough  to  reach  to  the 
farthest  point.  By  distributing  the  spelter  at  the 
proper  points  along  the  rod  it  may  be  placed  at  the 
right  points  by  turning  the  rod  over  after  inserting 
into  the  recess. 

Flux. — In  order  to  remove  the  oxides  produced 
under  brazing  heat  and  to  allow  the  brazing  metal  to 
flow  freely  into  place,  a  flux  of  some  kind  must  be 
used.  The  commonest  flux  is  simply  a  pure  calcined 
borax  powder,  that  is,  a  borax  powder  that  has  been 
heated  until  practically  all  the  water  has  been  driven 
off. 

Calcined  borax  may  also  be  mixed  with  about  15 
per  cent  of  sal  ammoniac  to  make  a  satisfactory 
fluxing  powder.  It  is  absolutely  necessary  to  use- 
flux  of  some  kind  and  a  part  of  whatever  is  used 
should  be  made  into  a  paste  with  water  so  that  it 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        197 

can  be  applied  to  the  joint  to  be  brazed  before  heat- 
ing. The  remainder  of  the  powder  should  be  kept 
dry  for  use  during  the  operation  and  after  the  heat 
has  been  applied. 

Preparing  the  Work. — The  surfaces  to  be  brazed 
are  first  thoroughly  cleaned  with  files,  emery  cloth  or 
sand  paper.  If  the  work  is  greasy,  it  should  be 
dipped  into  a  bath  of  lye  or  hot  soda  water  so  that 
all  trace  of  oil  is  removed.  The  parts  are  then  placed 
in  the  relation  to  each  other  that  they  are  to  occupy 
when  the  work  has  been  completed.  The  edges  to 
be  joined  should  make  a  secure  and  tight  fit,  and 
should  match  each  other  at  all  points  so  that  the 
smallest  possible  space  is  left  between  them.  This 
fit  should  not  be  so  tight  that  it  is  necessary  to  force 
the  work  into  place,  neither  should  it  be  loose  enough 
to  allow  any  considerable  space  between  the  surfaces. 
The  molten  spelter  will  penetrate  between  surfaces 
that  water  will  flow  between  when  the  work  and  spelter 
have  both  been  brought  to  the  proper  heat.  It  is,  of 
course,  necessary  that  the  two  parts  have  a  sufficient 
number  of  points  of  contact  so  that  they  will  remain 
in  the  proper  relative  position. 

The  work  is  placed  on  the  surface  of  the  brazing 
table  in  such  a  position  that  the  flame  from  the 
torches  will  strike  the  parts  to  be  heated,  and  with 
the  joint  in  such  a  position  that  the  melted  spelter 
will  flow  down  through  it  and  fill  every  possible  part 
of  the  space  between  the  surfaces  under  the  action 
of  gravity.  That  means  that  the  edge  of  the  joint 
must  be  uppermost  and  the  crack  to  be  filled  must 
not  lie  horizontal,  but  at  the  greatest  slant  possible. 
Better  than  any  degree  of  slant  would  be  to  have 
the  line  of  the  joint  vertical. 


198  WELDING 

The  work  is  braced  up  or  clamped  in  the  proper 
position  before  commencing  to  braze,  and  it  is  best 
to  place  fire  brick  in  such  positions  that  it  will  be 
impossible  for  cooling  draughts  of  air  to  reach  the 
heated  metal  should  the  flame  be  removed  temporarily 
during  the  process.  In  case  there  is  a  large  body  of 
iron,  steel  or  copper  to  be  handled,  it  is  often  advis- 
able to  place  charcoal  around  the  work,  igniting  this 
with  the  flame  of  the  torch  before  starting  to  braze 
so  that  the  metal  will  be  maintained  at  the  correct 
heat  without  depending  entirely  on  the  torch. 

"When  handling  brass  pieces  having  thin  sections 
there  is  danger  of  melting  the  brass  and  causing  it 
to  flow  away  from  under  the  flame,  with  the  result 
that  the  work  is  ruined.  If,  in  the  judgment  of  the 
workman,  this  may  happen  with  the  particular  job 
in  hand,  it  is  well  to  build  up  a  mould  of  fire  clay 
back  of  the  thin  parts  or  preferably  back  of  the 
whole  piece,  so  that  the  metal  will  have  the  necessary 
support.  This  mould  may  be  made  by  mixing  the 
fire  clay  into  a  stiff  paste  with  water  and  then  packing 
it  against  the  piece  to  be  supported  tightly  enough 
so  that  the  form  will  be  retained  even  if  the  metal 
softens. 

Brazing. — With  the  work  in  place,  it  should  be  wrell 
covered  with  the  paste  of  flux  and  water,  then  heated 
until  this  flux  boils  up  and  runs  over  the  surfaces. 
Spelter  is  then  placed  in  such  a  position  that  it  will 
run  into  the  joint  and  the  heat  is  continued  or 
increased  until  the  spelter  melts  and  flows  in  between 
the  two  surfaces.  The  flame  should  surround  the 
work  during  the  heating  so  that  outside  air  is  ex- 
cluded as  far  as  is  possible  to  prevent  excessive 
oxidization. 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        199 

When  handling  brass  or  copper,  the  flame  should 
not  be  directed  so  that  its  center  strikes  the  metal 
squarely,  but  so  that  it  glances  from  one  side  or  the 
other.  Directing  the  flame  straight  against  the  work 
is  often  the  cause  of  melting  the  pieces  before  the 
operation  is  completed.  When  brazing  two  different 
metals,  the  flame  should  play  only  on  the  one  that 
melts  at  the  higher  temperature,  the  lower  melting 
part  receiving  its  heat  from  the  other.  This  avoids 
the  danger  of  melting  one  before  the  other  reaches 
the  brazing  point. 

The  heat  should  be  continued  only  long  enough  io 
cause  the  spelter  to  flow  into  place  and  no  longer. 
Prolonged  heating  of  any  metal  can  do  nothing  but 
oxidize  and  weaken  it,  and  this  practice  should  be 
avoided  as  much  as  possible.  If  the  spelter  melts  into 
small  globules  in  place  of  flowing,  it  may  be  caused 
to  spread  and  run  into  the  joint  by  lightly  tapping 
the  work.  More  dry  flux  may  be  added  with  the 
spatula  if  the  tapping  does  not  produce  the  desired 
result. 

Excessive  use  of  flux,  especially  toward  the  end 
of  the  work,  will  result  in  a  very  hard  surface  on 
all  the  work,  a  surface  which  will  be  extremely  diffi- 
cult to  finish  properly.  This  trouble  will  be  present 
to  a  certain  extent  anyway,  but  it  may  be  lessened 
by  a  vigorous  scraping  with  a  wire  brush  just  as 
soon  as  the  work  is  removed  from  the  fire.  If  allowed 
to  cool  before  cleaning,  the  final  appearance  will  not 
be  as  good  as  with  the  surplus  metal  and  scale  re- 
moved immediately  upon  completing  the  job. 

After  the  work  has  been  cleaned  with  the  brush 
it  may  be  allowed  to  cool  and  finished  to  the  desired 
shape,  size  and  surface  by  filing  and  polishing.  When 


200  WELDING 

filed,  a  very  thin  line  of  brass  should  appear  where 
the  crack  was  at  the  beginning  of  the  work.  If  it 
is  desired  to  avoid  a  square  shoulder  and  fill  in  an 
angle  joint  to  make  it  rounding,  the  filling  is  best 
accomplished  by  winding  a  coil  of  very  thin  brass 
wire  around  the  part  of  the  work  that  projects  and 
then  causing  this  to  flow  itself  or  else  allow  the  spelter 
to  fill  the  spaces  between  the  layers  of  wire.  Copper 
wire  may  also  be  used  for  this  purpose,  the  spaces 
being  filled  with  melted  spelter. 

THERMIT    WELDING 

The  process  of  welding  which  makes  use  of  the 
great  heat  produced  by  oxygen  combining  with  alumi- 
num is  known  as  the  Thermit  process  and  was  per- 
fected by  Dr.  Hans  Goldschmidt.  The  process,  which 
is  controlled  by  the  Goldschmidt  Thermit  Company, 
makes  use  of  a  mixture  of  finely  powdered  aluminum 
with  an  oxide  of  iron  called  by  the  trade  name, 
Thermit. 

The  reaction  is  started  with  a  special  ignition 
powder,  such  as  barium  superoxide  and  aluminum, 
and  the  oxygen  from  the  iron  oxide  combining  with 
the  aluminum,  producing  a  mass  of  superheated  steel 
at  about  5000  degrees  Fahrenheit.  After  the  reac- 
tion, which  takes  from  30  seconds  to  a  minute,  the 
molten  metal  is  drawn  from  the  crucible  on  to  the 
surfaces  to  be  joined.  Its  extreme  heat  fuses  the 
metal  and  a  perfect  joint  is  the  result.  This  process 
is  suited  for  welding  iron  or  steel  parts  of  compara- 
tively large  size. 

Preparation. — The  parts  to  be  joined  are  thoroughly 
cleaned  on  the  surfaces  and. for  several  inches  back 
from  the  joint,  after  which  they  are  supported  in 


SOLDERING,  TRAZING  AND  THERMIT  WELDING       201 

place.  The  surfaces  between  which  the  met^l  will 
flow  are  separated  from  %  to  1  inch,  depending  on 
the  size  of  the  parts,  but  cutting  or  drilling  part  of 
the  metal  away.  After  this  separation  is  made  for 
allowing  the  entrance  of  new  metal,  the  effects  of 
contraction  of  the  molten  steel  are  cared  for  by  pre- 
heating adjacent  parts  or  by  forcing  the  ends  apart 
with  wedges  and  jacks.  The  amount  of  this  last 
separation  must  be  determined  by  the  shape  and 
proportions  of  the  parts  in  the  same  way  as  would 
be  done  for  any  other  class  of  welding  which  heats 
the  parts  to  a  melting  point. 

Yellow  wax,  which  has  been  warmed  until  plastic, 
is  then  placed  around  the  joint  to  form  a  collar,  the 
wax  completely  filling  the  space  between  the  ends 
and  being  provided  with  vent  holes  by  imbedding  a 
piece  of  stout  cord,  which  is  pulled  out  after  the 
wax  cools. 

A  retaining  mould  (Figure  55)  made  from  sheet 
steel  or  fire  brick  is  then  placed  around  the  parts. 
This  mould  is  then  filled  with  -a  mixture  of  one  part 
fire  clay,  one  part  ground  fire  brick  and  one  part 
fire  sand.  These  materials  are  well  mixed  and 
moistened  with  enough  water  so  that  they  will  pack. 
This  mixture  is  then  placed  in  the  mould,  filling  the 
space  between  the  walls  and  the  wax,  and  is  packed 
hard  with,  a  rammer  so  that  the  material  forms  a 
wall  several  inches  thick  between  any  point  of  the 
mould  and  the  wax.  The  mixture  must  be  placed 
in  the  mould  in  small  quantities  and  packed  tight 
as  the  filling  progresses. 

Three  or  more  openings  are  provided  through  this 
moulding  material  by  the  insertion  of  wood  or  pipe 
forms.  One  of  these  openings  will  lead  from  the 


202 


WELDING 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        203 

lowest  point  of  the  wax  pattern  and  is  used  for  the 
introduction  of  the  preheating  flame.  Another  open- 
ing leads  from  the  top  of  the  mould  into  this  pre- 
heating gate,  opening  into  the  preheating  gate  at  a 
point  about  one  inch  from  the  wax  pattern.  Open- 
ings, called  risers,  are  then  provided  from  each  of 
the  high  points  of  the  wax  pattern  to  the  top  of  the 
mould,  these  risers  ending  at  the  top  in  a  shallow 
basin.  The  molten  metal  comes  up  into  these  risers 
and  cares  for  contraction  of  the  casting,  as  well  as 
avoiding  defects  in  the  collar  of  the  weld.  After 
the  moulding  material  is  well  packed,  these  gate 
patterns  are  tapped  lightly  and  withdrawn,  except 
in  the  case  of  the  metal  pipes  which  are  placed  at 
points  at  which  it  would  be  impossible  to  withdraw 
a  pattern. 

Preheating. — The  ends  to  be  welded  are  brought 
to  a  bright  red  heat  by  introducing  the  flame  from 
a  torch  through  the  preheating  gate.  The  torch  must 
use  either  gasoline  or  kerosene,  and  not  crude  oil,  as 
the  crude  oil  deposits  too  much  carbon  on  the  parts. 
Preheating  of  other  adjacent  parts  to  care  for  con- 
traction is  done  at  this  time  by  an  additional  torch 
burner. 

The  heating  flame  is  started  gently  at  first  and 
gradually  increased.  The  wax  will  melt  and  may 
be  allowed  to  run  out  of  the  preheating  gate  by 
removing  the  flame  at  intervals  for  a  few  seconds. 
The  heat  is  continued  until  the  mould  is  thoroughly 
dried  and  the  parts  to  be  joined  are  brought  to  the 
red  heat  required.  This  leaves  a  mould  just  the  shape 
of  the  wax  pattern. 

The  heating  gate  should  then  be  plugged  with  a 
sand  core,  iron  plug  or  piece  of  fitted  fire  brick,  and 


204 


WELDING 


backed  up  with  several  shovels  full  of  the  moulding 
mixture,  well  packed. 

Thermit  Metal. — The  reaction  takes  place  in  a  spe- 
cial crucible  lined  with  magnesia  tar,  which  is  baked 
at  a  red  heat  until  the  tar  is  driven  off  and  the 
magnesia  left.  This  lining  should  last  from  twelve 


Figure  56. — Thermit  Crucible  Plug.  A,  Hard  burnt  magnesia 
stone  ;  B,  Magnesia  thimble  ;  C,  Refractory  sand ;  D,  Metal  disc ;  E, 
Asbestos  washer  ;  F,  Tapping  pin 

to  fifteen  reactions.  This  magnesia  lining  ends  at 
the  bottom  of  the  crucible  in  a  ring  of  magnesia  stone 
and  this  ring  carries  a  magnesia  thimble  through 
which  the  molten  steel  passes  on  its  way  to  the  mould. 
It  will  usually  be  necessary  to  renew  this  thimble 
after  each  reaction.  This  lower  opening  is  closed 
before  filling  the  crucible  with  thermit  by  means  of 
a  small  disc  or  iron  carrying  a  stem,  which  is  called 
a  tapping  pin  (Figure  56).  This  pin,  F,  is  placed 


SOLDERING,  BRAZING  AND  THERMIT  WELDING        205 

in  the  thimble  with  the  stem  extending  down 
through  the  opening  and  exposing  about  two  inches. 
The  top  of  this  pin  is  covered  with  an  asbestos, 
washer,  E,  then  with  another  iron  disc,  D,  and  finally 
with  a  layer  of  refractory  sand.  The  crucible  is  tapped 
by  knocking  the  stem  of  the  pin  upwards  with  a 
spade  or  piece  of  flat  iron  about  four  feet  long. 

The  charge  of  thermit  is  added  by  placing  a  few 
handfuls  over  the  refractory  sand  and  then  pouring 
in  the  balance  required.  The  amount  of  thermit  re- 
quired is  calculated  from  the  wax  used.  The  wrax  is 
weighed  before  and  after  filling  the  entire  space  that 
the  thermit  will  occupy.  This  does  not  mean  only 
the  wax  collar,  but  the  space  of  the  mould  with  all 
gates  filled  with  wax.  The  number  of  pounds  of 
wax  required  for  this  filling  multiplied  by  25  will 
give  the  number  of  pounds  of  thermit  to  be  used. 
To  this  quantity  of  thermit  should  be  added  1  per 
cent  of  pure  manganese,  1  per  cent  nickel  thermit  and 
15  per  cent  of  steel  punchings. 

It  is  necessary,  when  more  than  10  pounds  of 
thermit  will  be  used,  to  mix  steel  punchings  not 
exceeding  %  inch  diameter  by  %  inch  thick  with 
the  powder  in  order  to  sufficiently  retard  the  inten- 
sity of  the  reaction. 

Half  a  teaspoonful  of  ignition  powder  is  placed 
on  top  of  the  thermit  charge  and  ignited  with  a 
storm  match  or  piece  of  red  hot  iron.  The  cover 
should  be  immediately  closed  on  the  top  of  the 
cru-cible  and  the  operator  should  get  away  to  a  safe 
distance  because  of  the  metal  that  may  be  thrown 
out  of  the  crucible. 

After  allowing  about  30  seconds  to  a  minute  for 
the  reaction  to  take  place  and  the  slag  to  rise  to  the 


206  WELDING 

top  of  the  ciueible,  the  tapping  pin  is  struck  from 
below  and  the  molten  metal  allowed  to  run  into  the 
mould.  The  mould  should  be  allowed  to  remain  in 
place  as  long  as  possible,  preferably  over  night,  so 
as  to  anneal  the  steel  in  the  weld,  but  in  no  case 
should  it  be  disturbed  for  several  hours  after  pouring. 
After  removing  the  mould,  drill  through  the  metal 
left  in  the  riser  and  gates  and  knock  these  sections 
off.  No  part  of  the  collar  should  be  removed  unless 
absolutely  necessary. 


CHAPTER  IX 
OXYGEN  PROCESS  FOB  REMOVAL  OF  CARBON 

Until  recently  the  methods  used  for  removing  car- 
bon deposits  from  gas  engine  cylinders  were  very  im- 
practical and  unsatisfactory.  The  job  meant  dis- 
mantling the  motor,  tearing  out  all  parts,  and  scraping 
the  pistons  and  cylinder  walls  by  hand. 

The  work  was  never  done  thoroughly.  It  required 
hours  of  time  to  do  it,  and  then  there  was  always  the 
danger  of  injuring  the  inside  of  the  cylinders. 

These  methods  have  been  to  a  large  extent  super- 
seded by  the  use  of  oxygen  under  pressure.  The 
various  devices  that  are  being  manufactured  are 
known  as  carbon  removers,  decarbonizers,  etc.,  and 
large  numbers  of  them  are  in  use  in  the  automobile 
and  gasoline  traction  motor  industry. 

Outfit. — The  oxygen  carbon  cleaner  consists  of  a 
high  pressure  oxygen  cylinder  with  automatic  reduc- 
ing valve,  usually  constructed  on  the  diaphragm  prin- 
ciple, thus  assuring  positive  regulation  of  pressure. 
This  valve  is  fitted  with  a  pressure  gauge,  rubber  hose, 
decarbonizing  torch  with  shut  off  and  flexible  tube  for 
insertion  into  the  chamber  from  which  the  carbon  is  to 
be  removed. 

There  should  also  be  an  asbestos  swab  for  swabbing 
out  the  inside  of  the  cylinder  or  other  chamber  with 
kerosene  previous  to  starting  the  operation.  The 
action  consists  in  simply  burning  the  carbon  to  a  fine 
dust  in  the  presence  of  the  stream  of  oxygen,  this  dust 
being  then  blown  out. 

207 


208  WELDING 

Operation. — The  following  are  instructions  for  oper- 
ating the  cleaner : — 

(1)  Close  valve  in  gasoline  supply  -line  and  start 
the  motor,   letting  it  run   until   the   gasoline  is   ex- 
hausted. 

(2)  If  the  cylinders  be  T  or  L  head,  remove  either 
the  inlet  or  the  exhaust  valve  cap,  or  a  spark  plug  if 
the  cap  is  tight.    If  the  cylinders  have  overhead  valves, 
remove  a  spark  plug.     If  any  spark  plug  is  then  re- 
maining in  the  cylinder  it  should  be  removed  and  an 
old  one  or  an  iron  pipe  plug  substituted. 

(3)  Raise  the  piston  of  the  cylinder  first  to  be 
cleaned  to  the  top  of  the  compression  stroke  and  con- 
tinue this  from  cylinder  to  cylinder  as  the  work  pro- 
gresses. 

(4)  In  motors  where  carbon  has  been  burned  hard, 
the  cylinder  interior  should  then  be  swabbed  with 
kerosene  before  proceeding.    Work  the  swab,  saturated 
with  kerosene,  around  the  inside  of  the  cylinder  until 
all  the  carbon  has  been  moistened  with  the  oil.    This 
same  swab  may  be  used  to  ignite  the  gas  in  the  cyl- 
inder in  place  of  using  a  match  or  taper. 

(5)  Make  all  connections  to  the  oxygen  cylinder. 

(6)  Insert  the  torch  nozzle  in  the  cylinder,  open  the 
torch  valve  gradually  and  regulate  to  about  two  Ibs. 
pressure.     Manipulate  the  nozzle  inside  the  cylinder 
and  light  a  match  or  other  flame  at  the  opening  so 
that  the  carbon  starts  to  burn.     Cover  the  various 
points  within  the    cylinder    and   when    there   is   no 
further  burning  the  carbon  has  been  removed.     The 
regulating  and  oxygen  tank  valves  are  operated  in 
exactly  the  same  way  as  for  welding  as  previously 
explained. 

It  should  be  carefully  noted  that  when  the  piston  is 


OXYGEN  PROCESS  FOR  REMOVAL  OF  CARBON   209 

up,  ready  to  start  the  operation,  both  valves  must  be 
closed.  There  will  be  a  considerable  display  of  sparks 
while  this  operation  is  taking  place,  but  they  will  not 
set  fire  to  the  grease  and  oil.  Care  should  be  used  to 
see  that  no  gasoline  is  about. 


INDEX 


PAGE 

Acetylene    42 

filtering 78 

generators 60 

in  tanks 49 

piping    79 

properties  of    46 

purification  of   47 

Acetylene-air  torches   104 

Air 36 

oxygen  from 35 

Alloys 11,  20 

table  of 137 

Alloy  steel   15 

Aluminum 17 

alloys 24 

welding 130 

Annealing 27 

Anvil   172 

Arc  welding,  electric 160 

machines  .  . .  . : 166 

Asbestos,  use  of,  in  welding 58 

Babbitt   24 

Bending  pipes  and  tubes 176 

Bessemer  steel 16 

Beveling 115,  116 

Brass   22 

welding 132 

Brazing 155,  188,  192,  198 

electric    155 

heat  and  tools 193 

spelter   195 

Bronze 23 

welding   132 

Butt  welding 151 

211 


212  INDEX 

PAGE 

Calcium  carbide 43 

Carbide  43 

storage  of,  Fire  Underwriters '  Eules 45 

to  water  generator 64 

Carbon  removal 33 

by  oxygen  process 207 

Case  hardening  steel 32 

Cast  iron 12 

welding  150 

Champf  ering  113 

Charging  generator  69 

Chlorate  of  potash  oxygen 41 

Conductivity  of  metals 140 

Copper  18 

alloys 22 

welding  131 

Crucible  steel 16 

Cutting,  oxy-acetylene  33 

torches     103 

Dissolved   acetylene    50 

Electric  arc  welding 160 

Electric  welding   142 

troubles  and  remedies 155 

Expansion  of  metals 141 

Flame,  welding  121 

Fluxes 54,  180 

for  brazing  196 

for  soldering 189 

Forge  170 

fire  171 

practice 173 

tools  171 

tuyere  construction  of 170 

welding  182 

welding  preparation  178 

welds,  forms  of 184 

Forging    170 

Gas  holders 66,  77 

Gases,  heating  power  of 139 

Generator,   acetylene    60 

carbide  to  water 64 

construction    68 


INDEX  213 

Generator  PAGE 

location  of 84 

operation  and  care  of 71 

overheating    62 

requirements 61 

water  to  carbide 63 

German  silver 24 

Gloves    56 

Goggles   56 

Hand   forging    170 

Hardening  steel 27 

Heat  treatment  of  steel 25 

Hildebrandt  process 39 

Hose    58 

Injectors,    adjuster    99 

Iron   11 

cast   12 

grades  of   14 

malleable  cast   13 

wrought 13 

Jump  weld 185 

Lap  welding 154 

Lead    18 

Linde  process    38 

Liquid  air   oxygen 38 

Magnalium   24 

Malleable  iron  13 

welding     128 

Melting  points  of  metals 139 

Metal  alloys,  table  of 137 

Metals   •.   11 

characteristics  of 125 

conductivity  of 140 

expansion  of   141 

heat   treatment   of 11 

melting  points  of 139 

tensile    strength    of 140 

weight  of   141 

Nickel    20 

Nozzle  sizes,  tore!1 102 


214  INDEX 

PAGE 

Open   hearth    steel 17 

Oxy-acetylene  cutting    33 

welding  practice    106 

Oxygen    35 

cylinders   39 

weight  of   39 

Pipes,  bending 176 

Platinum 20 

Preheating     106,  203 

[Removal  of  carbon  by  oxygen  process 207 

Eesistance   method    of   electric   welding 142 

Eestoration    of    steel 132 

Kods,  welding   52 

Safety  devices 80 

Scarfing    179 

Solder    24 

Soldering    188 

flux 188 

holes    191 

seams     191 

steel  and  iron 192 

wires    191 

Spelter    195 

Spot  welding 143,  154 

Steel    14 

alloys    15,  21 

Bessemer 16 

crucible   16 

heat   treatment   of 25 

open  hearth   17 

restoration  of 132 

tensile  strength  of 15 

welding   150 

Strength   of   metals 140 

Tank  valves  85 

Tapering     114 

Tables  of  welding  information 136-141 

Tempering  steel    30 

Thermit    metal 204 

preheating    203 

preparation     200 

welding    188,  200 


INDEX  213 

PAGE 

Tin 19 

Torch    90 

acetylene-air 104 

care    101 

construction    100 

cutting    103 

high  pressure 96 

low  pressure 98 

medium  pressure 97 

nozzles 102 

practice    34,  118 

Valves,  regulating   86 

tank 85 

Water  37 

to  carbide  generator 63 

Welding  aluminum 130 

brass  132 

bronze  132 

butt : 151 

cast  iron  . . . . 127 

copper  131 

electric  142 

electric  arc 160 

flame  121 

forge  182 

information  and  tables 135-141 

instruments  85 

lap  154 

malleable  iron  128 

materials 33 

practice,  oxy-acetylene 106 

rods  52 

spot  143,  154 

steel  129 

table  57 

thermit 188,  200 

torches  90 

various  metals  125 

wrought  iron 129 

Wrought  iron 13 

welding  129 

Zinc   .  .   19 


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lustrated          1.50     ... 

Electric    Railway    Troubles   and   How   To 

Find   Them — Lowe    1.50     ... 

Electric    Power   Stations — Swingle    2.50     ... 

Electrical     Construction,     Modern.     Illus- 
trated       1.50 

Electrical   Dictionary,   Handy,   Weber 25     .50 

Electrical    Wiring    and    Construction    Ta- 
bles— Horstmann    &    Tousley 1.50 

Electricity,    Easy    Experiments    in — Dick* 

inson.      Illustrated     *.ox>    ••« 


Price. 
Titles.  Cloth.  Lecu 

Electricity  Made  Simple — Haskins.  Illus- 
trated    1.00  ... 

Electric  Railroading — Ay Imer- Small.  Il- 
lustrated    3.56 

Electro  -  Plating      Hand      Book — Weston. 

Illustrated     1.00  1.60 

Elementary    Electricity,     Up    To    Date — 

Aylmer-Small     1.25     . . . 

Estimator,     Modern,     for     Builders     and 

Architects — Hodgson     1.60     .... 

Examination  Questions  and  Answers  for 
Locomotive  Firemen — Wallace.  Illus- 
trated   1.59 

Examination  Questions  and  Answers  for 
Marine  and  Stationary  Engineers — 
Swingle.  Illustrated  1.50 

Elevators,  Hydraulic  and  Electric — Swin- 
gle. Illustrated  1.00  . . . 

Electrician's  Operating  and  Testing 
Manual — Horstmann  &  Tousley.  Illus- 
trated   1.6t 

Farm  Engines  and  How  to  Run  Them — 

Stephenson.      Illustrated     1.00     . . . 

Furniture  Making,  Home — Raeth.  Illus- 
trated   60  ... 


Gas  arid  Oil  Engine  Hand  Book — 

Brookes.  Illustrated  1.00  1.50 

Hand  Book  for  Engineers  and  Electri- 
cians— Swingle.  Illustrated.  Pocket 
Book  Style  3.00 

Hardwood  Finishing,  Up-to-date — Hodg- 
son. Illustrated  1.00  ... 

Horse  Shoeing,  Correct — Holmstrom.  Il- 
lustrated    1.00  ... 

Hot  Water  Heating,  Steam  and  Gas  Fit- 
ting— Donaldson.  Illustrated  1.50  ... 

Heating  and  Lighting  Railway  Passen- 
ger Cars — Prior  1.25  . . . 

Locomotive  Breakdowns,  with  Questions 

and  Answers — Wallace.  Illustrated 1.50 

Locomotive  Fireman's  Boiler  Instructor — 

Swingle 1.68 

Locomotive  Engineering — Swingle.  Illus- 
trated. Pocket  Book  Style 3.09 

Machine  Shop  Practice — Brookes.  Illus- 
trated    2.00  .  . . 

Mechanical  Drawing  and  Machine  Design 

— Westinghouse.  Illustrated 2.00  ... 

Motorman,  How  to  Become  a  Successful. 

Aylmer-Small.  Illustrated 1.60 

Motorman's  Practical  Air  Brake  Instruc- 
tor— Denehie  1'50 

Modern  Electric  Illumination,  Theory 
and  Practice — Horstmann  &  Tousley. 
Illustrated  2.0i 

Millwright's  Practical  Hand  Book — Swi»- 

gle.  Illustrated  i.OO  ... 

Modern  American  Telephony  In  All  Its 
Branches — Smith.  Illustrated -  *  4* 


Price. 
Titles.  Cloth.  Lea. 

Operation  of  Trains  and  Station  Work — 
Prior.  Illustrated  1.50 

Painting,  Cyclopedia  of — Maire.  Illus- 
trated    1.60  . . . 

Pattern  Making  and  Foundry  Practice — 
Hand.  Illustrated  1.50 

Picture  Making  for  Pleasure  and  Profit — 

Baldwin.      Illustrated    1.25     ... 

Plumbing,    Practical,    Up-to-Date — Clow. 

Illustrated 1.50    ... 

Railway  Roadbed  and  Track,  Construc- 
tion and  Maintenance  of — Prior.  Illus- 
trated   2.00 

Railway  Shop  Up-to-Date — Haig.  Illus- 
trated    2.00  ... 

Sheet    Metal    Workers'    Instructor — Rose. 

Illustrated    2.00     ... 

Signist's  Book  of  Modern  Alphabets — Del- 

amotte    1.50     ... 

Sign    Painting,    The    Art   of — Atkinson...      3.00     ... 

Stair  Building  and  Hand  Railing — Hodg- 
son. Illustrated 1.00  ... 

Steam    Boilers — Swingle.      Illustrated 1.50 

Steel    Square,    A    Key    to — Woods 1.50     ... 

Steel  Square,  Vol.  I — Hodgson.  Illus- 
trated    1.00  ... 

Steel  Square,  Vol.  II — Hodgson.  Illus- 
trated   1.00  ... 

Steel  Square,   A  B  C — Hodgson.. 50     ... 

Steel     Construction,     Practical — Hodgson. 

Illustrated    50    ... 

Storage     Batteries — Niblett     50     ... 

Sho'    Cards,    A    Show    At — Atkinson    and 

Atkinson     3.00     ... 

Stonemasonry,     Practical,     Self-Taught — 

Hodgson.      Illustrated    1.00     ... 

Telegraphy  Salf-Taught — Edison.  Illus- 
trated    1.00  ... 

Telephone  Hand-Book —  Illus- 
trated    1.00  ... 

Timber     Framing,     Light     and     Heavy — 

Hodgson    2.00     ... 

Toolsmith     and     Steel     Worker — Holford. 

Illustrated    1.50     ... 

Turbine,  The  Steam — Swingle.   Illustrated     1.00     ... 

Walschaert  Valve  Gear  Breakdowns  and 
How  to  Adjust  Them — Swingle.  Illus- 
trated    1.00  . . . 

Wiring     Diagrams,      Modern — Horstmann 

&   Tousley.      Illustrated    1.50 

Wireless     Telegraphy     and     Telephony — 

V.   H.   Laughter 1.00     ... 

Wood  Carving,  Practical — Hodgson.  Illus- 
trated    1.50  ... 

THE    BED    BOOK    SEBIES    OF   TBADE    SCHOOL 

MANUALS 
By   F.    Maire 

16  mo.,  Cloth,  Illustrated.  Price,  each,  $0.60 

Exterior  Painting,  Wood,  Iron  and  Brick. 
Interior  Painting,  Water  and  Oil  Colors. 
Colors,  What  They  Are  an*  What  to  Expect 

from    Them. 

Graining    and    Marbling. 
Carriage    Painting. 
The    Wood    Finisher. 


Twentieth  Century 
Machine  Shop  Practice 

By  L.  ELLIOTT  BROOKES 

The  best  and  latest  and  most 
practical  work  published  on  mod- 
ern machine  shop  practice.  This 
book  is  intended  for  the  practical 
instruction  of  Machinists,  Engin- 
eers and  others  who  are  interested 
in  the  use  and  operation  of  the 
machinery  and  machine  tools  in  a 
modern  machine  shop.  The  first 
portion  of  the  book  is  devoted  to 
practical  examples  in  Arithmetic, 
Decimal  Fractions,  Roots  of  Num- 
bers, Algebraic  Signs  and  Symbols, 
Reciprocals  and  Logarithms  of 
Numbers,  Practical  Geometry  and 
and  Mensuration.  Also  Applied 
Mechanics — which  includes:  The 
lever,  The  wheel  and  pinion,  The 
pulley,  The  inclined  planes,  The 
wedge  The,  screw  and  safety  valve 
— Specific  gravity  and  the  velocity 
of  falling  bodies — Friction,  Belt 
Pulleys  and  Gear  wheels. 

Properties  of  steam,  The  Indi- 
cator, Horsepower  and  Electricity. 

Tb«».  latter  part  of  the  book  gives  full  and  complete  information 
upon  the  following  subjects:  Measuring  devices,  Machinists'  tools. 
Shop  tools,  Machine  tools,  Boring  machines,  Boring  mills.  Drill 
presses,  Gear  Cutting  machines,  Grinding  Machines,  Lathes  and  Mill- 
ing machines.  Also  auxiliary  machine  tools.  Portable  tools,  Miscella- 
neous tools,  Plain  and  Spiral  Indexing  machines,  Notes  on  Steel,  Gas 
furnaces.  Shop  talks,  Shop  kinks.  Medical  Aid  and  over  Fifty  tables. 

The  book  is  profusely  illustrated  and  shows  views  of  the  latest 
machinery  and  the  most  up-to-date  and  improved  belt  and  motor- 
driven  machine  tools,  with  full  information  as  to  their  use  and  opera- 
tion. It  has  been  the  object  of  the  author  to  present  the  subject 
matter  in  this  work  in  as  simple  and  not  technical  manner  as  is 
possible. 

12mo,  cloth,  636  pages,  456  fine  illustrations,  price,  $2.00 

Sold  by  Booksellers  generally,  or  sent  postpaid  to 
any  address  upon  receipt  of  Price  by  the  Publishers 

FREDERICK  J.  DRAKE  &  CO. 

PUBLISHERS  CHICAGO,  U.  S.  A. 


THE  AUTOMOBILE  HAND-BOOK 

OVER  200,000  SOLD 
By  ELLIOTT  BROOKES,  Assissted  by   Other   Well-Known  Experts 

Revised  and  Enlarged  New  Edition— The  largest  and   most  practical 

work  published.     Used  by  all  up-to-date  automobile  schools  as 

their  everyday  text-book.  over    720  pages   and 

over  329  illustrations.   Full  Leather  Limp.  Round 

Corners,  Red  Edges.    Price,  $2.00. 

At  the  present  time  nearly  all  automobile 
troubles  or  breakdowns  may,  in  almost 
every  case,  be  traced  to  the  lack  of  knowl- 
edge or  carelessness  of  the  owner  or  opera- 
tor of  the  car,  rather  than  to  the  car  itself. 
The  automobile  hand  book  is  a  work  of 
p  actical  information  for  the  use  of  owners, 
operators  and  automobile  mechanics,  giv- 
ing full  and  concise  information  on  all 
questions  relating  to  the  construction,  care 
and  operat  .on  of  gasoline  and  electric  auto- 
mobiles, including  road  troubles,  motor 
troubles,  -rbureter  troubles,  ignition 
troubles,  battery  troubles,  clutch  troubles, 
starting  troubles.  With  numerous  tables, 
useful  rules  and  formula,  wiring  diagrams 
and  over329illustrations. 

Special  efforts  have  been  put  forth  to 
treat  the  subjects  of  ignition,  and  igni- 
tion devices,  in  a  manner  befitting  their 
importance.  A  large  section  has  been 
devoted  to  t  ese  subjects,  including  bat- 
teries, primary  and  secondary,  magnetos. 

carburators,  spark  plugs,  and  in  fact  all  devices  used  in  connection  with 
the  production  of  the  spark.  Power  transmissio  is  thoroughly  discussed, 
and  the  various  systems  of  transmitting  the  power  from  the  motor  to  the 
driving  axle  are  analyzed  and  compared. 

The  perusal  of  this  work  for  a  few  minutes  when  troubles  occur,  will 
often  not  only  save  time,  money,  and  worry,  but  give  greater  confidence 
in  the  car,  with  regard  to  its  going  qualities  on  the  road,  when  properly 
and  intelligently  cared  for. 

A  WORD  TO  THE  WISE 

The  time  is  at  hand  when  any  person  caring  for  and  operating  any 
kind  of  self-propelling  vehicle  in  a  public  or  private  capacity,  will  have  to 
undergo  a  rigid  examination  before  a  state  board  of  examiners  and  secure 
a  license  before  they  can  collect  their  salary  or  get  employment. 

Already  New  York  State  has  enacted  such  c.  law  and  before  long,  with 
a  positive  certainty  every  state  in  the  Union  will  pa»s  such  an  ordinance 
for  the  protection  of  life  and  property. 

Remember  this  is  a  brand  new  book  from  cover  to  cover,  just  rrom 
the  press —  New  Edition — and  must  not  be  confounded  with  any  former 
editions  of  this  popular  work. 

Sent  prepaid  to  any  address  upon  receipt  of  price 

FREDERICK  J.  DRAKE  &  CO.,  Publishers 

1325  Michigan  Avenue.       •      •      -      CHICAGO,  U.  S.  A. 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  oo  CENTS  ON  THE  FOURTH 
DAY  ANH  <->  $1-00  ON  THE  SEVENTH  DAY 


NOV    6  1935 


14 


193; 


U.C.BERKELEY  LIBRARIES 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


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